greg goebel / public domain
* VECTORS is an original newsletter of fact and commentary on aerospace, technology, science, and historical topics.
* It doesn't take much thought to realize that a crash-test dummy is a more sophisticated piece of gear than a department-store manikin, but a close examination of exactly what goes into a crash-test dummy is still a surprise.
Welcome to Denton ATD, a 170-employee company with facilities in the states of Michigan and Ohio, founded by Robert A. Denton in 1969. The company's bread and butter is the "Hybrid III" crash dummy, or more formally "anthropomorphic test device" -- an inanimate model of a human being that helps determine, for example, how a human would respond to a car crash, and how to implement devices to improve passenger safety.
The Hybrid III consists of about 350 components, including a large number of components designed to simulate the elements of the human body. The parts are fabricated by Denton, from the vinyl skin to the metal bones. The neck is particularly complicated since the human neck is so prone to injury from collisions. The dummies are "wired" with sensors to track such items as the compression of the chest on a seat belt or the torque on the neck during a rapid deceleration. Researchers have "calibrated" the effects of such events using impact and deceleration tests on human cadavers, pig carcasses, and sometimes graduate students.
Denton didn't start out making dummies, instead originally manufacturing force and torque sensors, called "load cells", which are used in a wide range of equipment. A load cell is a relative of the strain gauge, which consists of a wire loop whose electrical resistance changes when the substrate it is mounted on undergoes strain. In the case of a load cell, the substrate is a small metal beam that deforms when stretched or compressed; a set of load cells can be mounted at different orientations to provide measurements along multiple axes. Denton still produces their own load cells, which is a nitpicking, painstaking job.
The Hybrid III not only features load cells, it also is fitted with accelerometers and potentiometers. Modern accelerometers are fabricated in silicon like microcircuit chips, but potentiometers are basically old-fashioned, being variable resistors in which an arm moving over the surface of a resistor measures deflection.
All the components of a Hybrid III are carefully assembled to build a complete dummy. Ironically, before a crash-test dummy goes on to a life of torture, it must be tortured to ensure that it works properly, being beaten by machines until all is validated. The graduating dummy is awarded a certification stamp and packed away in a shipping container.
Hybrid IIIs are, not too surprisingly, available in a wide range of sizes. The most popular model is the "50th percentile male", which is 1.75 meters (X feet X inches) tall -- or it would be that tall if it could stand up, but it can't -- and weighs 78 kilograms (172 pounds). It is designed to simulate an average North American male. There are models for larger and smaller males, a range of females, and a range of kids. The Denton catalog lists 40 different types of dummies and the company ships up to 25 dummies a month, mostly to the global automotive industries. The dummies are also used to test roller coasters, airplanes, helicopters, school buses, and anything else that can crash. A Denton official commented: "There were some applications where we had no clue what they were doing. It was proprietary or government-related. The dummies left brand-new, they came back in parts."
The specifications for the Hybrid III are not a secret. Anyone can obtain them from the US National Highway Traffic Safety Administration (NHTSA) as "Docket 71-14". The idea of the open spec is to ensure the consistency of safety standards -- in theory, one dummy should be equivalent in terms of test results to another. Safety agencies elsewhere have much the same "open source" policy. Anyone could manufacture a Hybrid III dummy, except for the fact that it's not trivial to build. Denton has the experience and expertise to do a good job of it and newcomers might find it hard to compete. In fact, Denton has only one competitor at its level of capability, First Technology Safety Systems of Plymouth, Michigan.
One of the other implications of this issue is that the specs for the dummy are frozen, and have been since 1972, when the US government issued the "Federal Motor Vehicle Safety Standard No. 208, Occupant Crash Protection". The origins of the act go back to just after World War II, when the US Air Force (USAF) was introducing ejection seats into combat aircraft. A USAF medical researcher named Colonel John Stapp pioneered bioresearch into the effects on humans of rapid acceleration and deceleration, with his work involving deceleration runs on rocket sleds. Stapp performed some of the test runs himself, with photostrips surviving of the contortions of his face, as well as images of the massive black eyes he suffered. An annual conference of car-crash testers, biomechanics researchers, and other safety industry officials is named the "Stapp Car Crash Conference" in his honor.
A range of other dummies were later developed by various industries. The aerospace industry produced the "Model T Parachute Dummy", "Torso", and "Dynamic Dan". The medical profession obtained "Rando for Radiotherapy", "Dexter Dental Dummy", and the "Phantom" family -- "Cardiac Chest Phantom", "Nuclear Phantom", and "Organ Scanning Phantom".
Car-crash test dummies were an outgrowth of public activism in the late 1960s and early 1970s that created pressure for safer vehicles. In 1971 General Motors (GM), which had been working on prototype dummies, decided to combine parts of two competing designs -- one from Alderson Research Labs and the other from Sierra Engineering. The result was the "Hybrid I" dummy. The Hybrid I of course led to the "Hybrid II" and the Hybrid III, which was built specifically for the NHTSA and was established by the agency as an official standard in the late 1970s. There was also the competing "Sierra" family -- "Sierra Sam", "Sierra Stan", "Sierra Susie", "Sierra Saul", little "Sierra Sammy", and "Sierra Toddler" -- which have now been retired.
There has been continued development of dummies, leading to the "Side-Impact Dummy (SID)" series: "SID", "EuroSID", "BioSID", and "WorldSID". As with the Hybrid series, the SIDs are government standards that are implemented by vendors such as Denton. WorldSID is regarded as the most advanced dummy now available. It was designed by a global consortium of industry, government, and academic experts, with the goal of harmonizing test protocols and safety standards. It can record 258 different measurements in a single test, and the pricetag can run to $350,000 USD -- more than twice as much as a Hybrid III.
Research is ongoing to build even better dummies at automotive manufacturers, government agencies, and academic organizations. Denton is working on a new sensor system called the "RibEye", in which each of a dummy's 12 ribs are fitted with a LED, with two light-tracking sensors on the dummy's spine. The RibEye can track the movement of the ribs in all three dimensions to 1 millimeter and is a great improvement over potentiometers.
The company is also involved in a project named "FOCUS", standing for "Facial & Ocular Countermeasure for Safety Headform", working with the US Army Aeromedical Research Laboratory and the Center for Injury Biomechanics -- run jointly by Virginia Tech College of Engineering, in Blacksburg, and Wake Forest University School of Medicine, in Winston-Salem NC. The product of the effort is an improved dummy "face", with silicone-based eyeballs and a set of load cells arranged around the bones of the face. Given better protective armor for soldiers, eye injuries have become proportionally more common; the Army wants to obtain FOCUS to evaluate helmets, goggles, and vehicle protective features. FOCUS also has civilian applications, such as tests for airbag shock and sports injuries.
* We tend to think of technology in terms of machines or software, but technology can also be embodied in an idea: for example, the logical or numerical procedures known as "algorithms". Algorithms are also a surprisingly pervasive technology, being widely used in getting things done. One example is the algorithm used to confirm the validity of credit-card numbers. Credit-card numbers are long and it's easy to make a mistake in entering them. Since so many credit-card transactions are being performed at all times, it's important to figure out a quick and easy way of determining if a bogus number has been input, instead of trying to access an account only to find out it doesn't really exist. The solution was developed by an IBM researcher named Hans Luhn and is unsurprisingly known as the "Luhn algorithm".
The numbers on a credit card define the card type, the card issuer, and the card account number. The last number is defined to support the Luhn algorithm, which works as follows:
This is a simple example of the use in algorithms in business. For a more
elaborate example, consider the problems faced by United Parcel Service
(UPS), which has to efficiently plan the delivery of vast numbers of packages
every day. Suppose a UPS delivery truck has to deliver to 25 separate
locations. The number of possible routes in this case is very large, since
there are 25 possible first stops; 24 possible second stops for each first
stop; 23 possible third stops for each second stop; and so on. This gives
the number of possibilities as:
25 * 24 * 23 * ... 3 * 2 * 1 = 1.55E15
The issue is further complicated by real-world factors such as specified
dropoff and pickup times. UPS has put a lot of money into solving the
"traveling salesman" problem, as this puzzle is broadly known. To plan the
movements of aircraft, the company worked with the Massachusetts Institute of
Technology (MIT) to developed a program named VOLCANO -- "Volume, Location, &
Aircraft Network Optimizer". It was introduced in 2000 and is used by three
UPS groups -- one to plan for deliveries at the peak season between
Thanksgiving and Christmas, one to plan schedules for the next two to four
months, and one to plan the resources required -- personnel, facilities,
aircraft -- to support business over the next two to ten years. Getting
scheduling wrong can be very expensive, either in terms of dissatisfied
customers and lost business, or in terms of half-empty leased aircraft;
although VOLCANO was expensive to write, it has more than paid for itself in
practice.
Many other businesses also rely on such "optimization" algorithms. Telecom companies use them to route phone calls and help retrieve web pages efficiently. Manufacturers and retailers use them to optimize supply chains. Call centers use them to prioritize incoming calls, based on such variables as the reason for the call, the location of the caller, and the length of the queues that the staff have to deal with.
One of the complications of optimization is that the problem may feature several "dimensions". For example, a package-delivery scheme must not only take into consideration the distances between delivery "nodes" but also the speed of traffic along each "vertex" between the nodes -- which may vary considerably at different times of day, for example going to a crawl at rush hour. Where such calculations become particularly tricky is when they have to be adapted in "real time". UPS is now working on a system that will permit changes in delivery schedules while the driver is making deliveries. The concept is much along the lines of that of the way an automotive satellite navigation system adjusts its course recommendations if a driver doesn't take a suggested turn.
Such considerations are particularly important to internetworking. Routing algorithms have traditionally simply focused on connections, without much consideration of congestion -- meaning that some connections may be overwhelmed while others remain relatively idle. Telecom operators are now working on improved optimization software that can provide "dynamic" routing, changing paths as congestion rises and falls to ensure better use of the communications network. Airports also have an interest in such algorithms, since they can help relieve the waits of passengers in airliners queued up to take off. This is a complicated problem since safety requirements demand a delay between takeoffs, and faster aircraft can take off more rapidly; there is also the issue of how many passengers an airliner is carrying. Traditionally, controllers have solved the "departure problem" manually, but now software is being developed to tackle the job.
* Optimization is one of the big domains of algorithms in business. Another major domain is statistical analysis. UK supermarket leader Tesco, for example, has a "Clubcard" scheme that monitors purchases by 13 million members across 55,000 product lines. The analysis system was developed by a company named Dunnhumby and uses what the engineers there call a "rolling ball" algorithm. Each product is assigned a set of "attributes", such as "easy to cook" or "value for money" or "adventurous" or "fresh". A product such as ostrich burgers would get a high score on the "adventurous" scale. However, the scale does not merely rate the product but also rates the customers who buy the product. The system tracks what other products customers willing to be "adventurous" are buying, even if they are bland items such as milk or margerine, and ups their rating on the "adventurous" scale. As associations between products grow weaker on one scale, they necessarily obtain a higher rating on a complementary scale, with the "ball rolling" from one scale to another. The ultimate product is a dynamic map of customer segmentation that Tesco can use to target sales pitches.
Statistical analysis is also used to monitor fraud -- for example, some insurers used fraud-detection software that checks claims against a list of items such as the day of the claim (frauds are most common on Mondays, it seems because people like to hatch plots on weekends); the age of the object of concern in the claim (old cars are much more often the subject of frauds than new ones); and the stridency of the claimant (people trying to pull off frauds have a tendency to raise a fuss in hopes of snowing the insurance agent). All credit card companies have systems to monitor for fraud.
Yet another major application of algorithms are internet search strategies, the techniques by which Google, MSN, and Yahoo! attempt to obtain the best matches to queries. One of the reasons that such statistical analysis has become more important is because for the first time businesses have the means to obtain data at a level of detail undreamed-of 50 years ago, and trying to sort out the flood is a full-time job. The availability of such torrents of data has also tempted businesses to do everything possible to exploit the information, in particular to concoct sales pitches tailored for specific customers.
* While algorithms are important to businesses, they are not necessarily important to all businesses. Retailers, telecom firms, and utilities have a big need for them, while home insurers and manufacturers of high-margin, profitable products do not. It also not cheap or easy to implement algorithms in software; not only is there the issue of coding them reliably, but also the issue of ensuring that users don't have to be rocket scientists to interface with the system. There is also the issue that algorithms are ultimately blind: they can make recommendations, but it is up to the humans in the loop to make the ultimate decision, for example on whether a customer making an insurance claim is a fraud. However, with such a flood of data to deal with humans can use all the help they can get, and algorithms are being continually improved in hopes of providing that help.
* Industrial sensors are an item that we take for granted, but which are found almost everywhere -- in factories, power systems, building heating and ventilation systems, and so on. In general, sensors are analog devices, changing resistance or producing a different voltage in response to the parameters they are supposed to measure. The sensors are wired into a central data-acquisition system that converts the outputs to the proper values for use by a computer control system.
The conversion of sensor inputs leads to possible confusion, since a data-acquisition system has to be correctly programmed to perform the right conversion, with the output curves described on data sheets. This gives plenty of opportunity to get things wrong. A new industrial specification designated "IEEE 1451.4" has been created to make life easier.
A "smart sensor" as described by IEEE 1451.4 has a low-cost industrial networking interface bundled along with the leads providing the inputs to the data acquisition system. The sensor also contains a description of its operation in a resident ROM, called a "Transducer Electronic Data Sheet". When a smart data-acquisition system is hooked up to a smart sensor, the data-acquisition system reads the TEDS data out of the sensor and automatically sets up the proper calibration for the sensor.
Since industrial control systems tend to stay in place for a long time, obviously a smart data-acquisition system will have to deal with old dumb sensors that don't have a TEDS. The standard addresses this problem using a "virtual TEDS (vTEDS)", which is TEDS information obtained from an online database keyed to the sensor model number. A vTEDS is clearly a stopgap, and it's unlikely that they will ever be available for every possible old sensor. However, the IEEE 1451.4 spec lays the groundwork for a future system of smart sensors.
* BOHR IN THE USA: By that time, Szilard wasn't the only voice raising concerns over the atomic demon. The Nazi leash on Denmark had been loose up to the summer of 1943; Hitler had no particular issues with the Danes, and Denmark was an agricultural powerhouse, helping keep Germany fed. Even Danish Jews were generally left alone. However, by early 1943 tensions between the Danes and the occupying power were on the increase, aggravated by the fact that the writing was beginning to appear on the wall for Hitler's Nazi empire. His weak-tea Fascist ally Mussolini resigned and was arrested on 25 July, an act that would be soon followed by the surrender of Italy to the Allies.
On 28 August, the German occupation authorities demanded that the Danish government take harsh measures to suppress civil unrest. The king and the government refused, and Denmark was reoccupied the next day. The Germans planned to deport the 8,000 or so Danish Jews to death camps in late September, but in one of the stranger stories of the war a German officer tipped off the Danish authorities about the raid, and the Danes hid away most of the Jews. The officer in question had a long history of human-rights abuses and it is generally thought he had a less than altruistic motive in tipping off the Danes, but nobody's sure of exactly what it was.
There was also to be a roundup of prominent and defiant Danes, with Niels Bohr near the top of the list. On 29 September he and his wife Margrethe took a motorboat ride to Sweden; their sons would follow later, with the family settling in Stockholm. There he appealed to the Swedish government to offer to take in Denmark's Jews, and on 2 October the Swedes broadcast an offer of asylum over the radio, with the Jews taking up the offer.
Unfortunately, Stockholm was rotten with Nazi agents and there were fears for Bohr's safety. Word of his escape from Denmark had got back to Britain, and Lord Cherwell sent an invitation for him to come to the UK, which was accepted. Given that the Axis effectively surrounded Sweden, physical communications between Britain and Sweden were by twin-engine British Mosquito light bombers, which could fly fast and high, avoiding interception while they carried small cargoes of mail and precision Swedish ball bearings. They could also carry a passenger in the bombbay, which was fitted up to make it as comfortable as possible under the circumstances.
There was no way that Bohr could take his whole family with him. On 6 October 1943, Bohr flew the "ball bearing express" to the UK, wearing a flight suit and an oxygen mask. He had some difficulties with the oxygen mask and passed out. The pilot was keeping tabs on his passenger via an intercom, and when no answers were forthcoming from the bombbay, the flight crew took the aircraft down to lower altitude; Bohr arrived in Scotland unharmed. His son Aage, also a physicist, flew in a week later.
James Chadwick briefed Bohr on the progress in the atomic bomb program, which astounded Bohr. Bohr had a few surprises of his own for the British as well, showing them the sketch Heisenberg had drawn of a heavy-water reactor. Those who knew what it might represent were startled, and had also received intelligence that the Norsk Hydro plant in Norway was back in operation. The USAAF hit the plant with 140 Boeing B-17 Flying Fortress bombers at mid-day on 16 November. The bombs were off target; still, they destroyed some of the plant support facilities and shut it down. The Germans contemplated relocating heavy water work to a more secure site in Germany, but the Norwegian resistance movement was keeping an eye on matters. A few months later, in February 1944, the Germans tried to ship out such stocks of heavy water as had been accumulated at the plant -- but the resistance sank a ferry carrying the barrels, with dozens of Norwegians drowning in the sinking. The German atomic research effort then came to an effective halt.
By that time Neils Bohr and his son Aage were at Los Alamos, on the British payroll along with a gaggle of other researchers, including James Chadwick, Otto Frisch, Rudolf Peierls, and yet another German physicist, named Klaus Fuchs. Fuchs was a very precise man, who Peirels' wife Genia nicknamed "Penny-In-A-Slot" since he would only speak when spoken to, responding to a question after a moment's thought with a neatly-thought-out and articulate answer. He would end up playing a more significant role in the program than anyone on the Manhattan Project conceived at the time.
In any case, Churchill wanted Britain to maintain a partnership in the atomic bomb program and the British team was accepted into the fold. The expatriates found the USA full of luxuries unheard-of in wartime Britain; exactly what they thought of the arid open spaces of New Mexico after living in the damp green hills of England was less clear.
* BOHR'S ARMS-CONTROL CAMPAIGN: The Bohrs had been named "Nicholas & James Baker" by Army security; they were referred to as "Uncle Nick & Jim" by the Los Alamos staff. The staff were also extremely interested when Bohr showed them Heisenberg's sketch of a heavy water reactor. It didn't look like a weapon, but Oppie was nervous enough to set up a committee to investigate if such a reactor could be used as one. The conclusion was that device built on such principles would be no more effective than a TNT bomb of the same size.
Although the rest of the British team set up home at Los Alamos, Bohr was merely a tourist, saying later: "They didn't need my help in making the atomic bomb." His concern, much like Szilard's, was simply how it would be used, what arrangements would be made in the postwar period to ensure that the bomb stayed under control. On arrival in the US in Washington DC that December, Bohr had met up with Supreme Court Justice Felix Frankfurter, the two having met in 1933 in London as part of the effort to rescue exiled German scientists. Frankfurter was a Vienna-born secular Jew who was a long-time advisor to Franklin Roosevelt; the physicist and the justice didn't have much time to chat at the time, but when Bohr returned to Washington DC in mid-February, he looked up Frankfurter in hopes of opening a channel to Roosevelt.
There was the problem that Frankfurter was not cleared on the Manhattan Project, but Frankfurter was able to second-guess Bohr's intent to a degree. Frankfurter had a vague knowledge of a "significant" military program that he just referred to as "X" and had something to do with physics, and the two men were able to chat in general terms about "X" without focusing on any details. When the two men met again in late March, Bohr learned that Frankfurter had indeed discussed matters with the president, who told the justice that he was "worried to death" over the matter and was "eager" to discuss "proper safeguards".
All this sounded promising, but the British were the key partner in the atomic alliance, and it wasn't a question of the Americans just making decisions on their own -- the British had to be in the loop, all the more so because Bohr was in the USA under British sponsorship. Roosevelt made it clear that Bohr had to discuss matters with Churchill to get things rolling. In early April, Niels Bohr and his son flew to Britain in a military aircraft -- to find Churchill in no particular hurry to discuss things. Bohr went to Number 10 Downing Street on 16 May, escorted by Lord Cherwell, to talk with Churchill, who became downright hostile: "He scolded us like two schoolboys!" -- as Bohr described it later. Churchill had no patience with highflown ideas about the postwar control of the atomic bomb, saying: "After all, this new bomb is just going to be bigger than our present bombs. It involves no difference in the principles of war. And as for any post-war problems, there are none that cannot be amicably settled between me and my friend, President Roosevelt."
* Bohr persisted in his efforts, but his work on the politics of the atomic bomb had reached a dead end. Although Churchill wanted to keep the bomb an Anglo-American monopoly, Bohr and others knew that once the atomic bomb had been unveiled, others would soon have it -- and it wasn't really like any other bomb, merely bigger. It was a weapon that could possibly destroy civilization, even exterminate humanity.
The conclusion of the war was not in doubt by that time. On 6 June, an Allied force landed on the beaches of Normandy, and soon Hitler's Reich would be squeezed in a vise between the Soviets and the Western Allies. In the Pacific, the Allies were methodically grinding down Japan's outposts, capturing strategically important islands and letting the others rot in isolation. The assault on the Marianas, on Japan's inner defensive ring, began in mid-June, resulting not only in the loss of an important Japanese outpost but in the effective crippling of Imperial Japanese Navy air power. The ground fighting in the Marianas had been vicious, but that had been expected. What had not been expected was the fact that tens of thousands of Japanese civilians on the island of Saipan, believing propaganda that they would be abused by the Americans, threw themselves over the cliffs into the sea. The demonstration that the Japanese preferred death to surrender suggested that bringing the war in the Pacific to a successful end might be even more difficult than had been believed.
In late June the Bohrs went back to Washington DC, to sweat in the sticky heat of the summer there. Having gone nowhere in London, Bohr worked to retrieve the situation by writing an extended memorandum to Roosevelt. In the memorandum, Bohr emphasized that atomic bombs were not like other weapons, that once nuclear weapons were in widespread service, nobody would be able to win an all-out war. The only result would be mutual destruction. To build up massive stockpiles of nuclear weapons would decrease security because it would give a nation an incentive to strike first before it was destroyed itself. Bohr advocated a program of arms control, with limits set by nations on the production and deployment of atomic weapons, and verification schemes implemented to ensure that nobody cheated.
Frankfurter passed the memorandum along to Roosevelt on 5 July. The president met with Bohr privately on 26 August and seemed very enthusiastic about Bohr's ideas, even giving Bohr the impression that the Dane might go to the Soviet Union for discussions. However, once again Roosevelt was a politician, and being agreeable didn't imply any commitment. In late September, Roosevelt met with Churchill in Quebec -- to emerge from the meeting in step with Churchill's negative attitude towards arms control. In fact, when Churchill heard that Bohr was extending feelers to Soviet physicists, Churchill found this treasonous, complained that the exchange between Bohr and Justice Frankfurter was a serious breach of security, and suggested Bohr ought to be arrested. Roosevelt was never as blunt as Churchill but was in agreement with him in principle. Bohr's efforts were effectively at an end.
* Incidentally, in the wake of the Normandy invasion, a special force set up by Groves late in the previous year and codenamed ALSOS went into operation. Its mission was to obtain intelligence on the German atomic bomb program. Somewhat puzzlingly, despite the fact that Szilard and many other physicists had been warning about the Nazi nuclear effort well before America entered the war, no specific intelligence program had been set up to find out what the Germans were up to -- and in fact Groves only set up ALSOS when General Marshall, chairman of the joint chiefs, asked him to. It seems that Groves feared an intelligence effort might cut both ways: those working in such an effort would have to be briefed on essential details of the American program in order to know what to look for, and if they were captured it might compromise Los Alamos' security. Somewhat uncomfortably, the codename ALSOS turned out to mean "grove" in Greek, which Groves thought was too big a clue -- but changing it would draw more attention to the matter and so it stayed as it was.
ALSOS was under the direction of Lieutenant Colonel Boris Pash, an Army security man, with a past history as an FBI-trained Red hunter. Pash was competent and energetic, though a bit paranoid: he was among those who were convinced Oppenheimer was a Red spy. ALSOS was only supposed to follow the troops, but Pash and his men turned out to be willing to move ahead of the battle lines when they thought an opportunity justified it. [TO BE CONTINUED]
* DNA REVEALED: While the evolutionists worked on the modern synthesis, the puzzle of how DNA, or whatever molecule that encoded heredity, stored a "genetic code", the instructions for building an organism and keeping it alive, had proven sufficiently intriguing to attract some of the best minds in physics. The Danish physicist Niels Bohr (1885:1962) and his student Max Delbrueck (1906:1981) examined the physical constraints on the mechanisms of heredity, and their thoughts and those of others were presented to the public in 1945 by the Austrian physicist Erwin Schroedinger (1887:1961) in a popular landmark book titled WHAT IS LIFE?
Schroedinger speculated that the genetic code was embodied in an "aperiodic crystal" that consisted of a string of a few different elements. The order of the elements provided the genetic code, just as a simple dot and dash could encode messages in Morse code. Schroedinger was a theoretical physicist and had a weak grasp of practical biochemistry, but his basic ideas were astute and proved very influential. They inspired a young American biochemist named James Watson (born 1928), who was working in Cambridge, England, in collaboration with a British physicist named Francis Crick (1916:2004) in studies of DNA.
The Austrian biochemist Erwin Chargaff (1905:2002) had discovered that the four nucleotides that make up the DNA chain -- adenine, thymine, cytosine, and guanine (A, T, C, and G) -- had a clear regularity: the amount of A in DNA was the same as the amount of T, and the amount of C was the same as the amount of G. This was a significant clue to the structure of DNA, and another major clue was provided in 1952 when Rosalind Franklin (1920:1958), a collaborator with Crick and Watson, performed X-ray crystallography studies of DNA.
In 1953, Crick and Watson used the clues to develop their famous "double helix" model of DNA, with DNA composed not of a single polymeric chain but a pair of linked chains, conceptually resembling a ladder twisted into a spiral. The bases were linked together by alternating sugar and phosphate groups, with the steps of the ladder consisting of the "base pairs" A and T, or C and G, linked together by a relatively weak bond. The DNA molecule could replicate by splitting down the middle of the helix along these weak bonds, with the two half-chains then reconstituting themselves into two full chains by linking new nucleotides. Mutations arose through errors in the DNA replication process.
* The sequence of the nucleotide "bases" in the DNA molecule clearly defined the genetic code, but Crick and Watson did not know how to interpret the sequences. By 1964, through the work of Marshall Nirenberg (born 1927), H. Gobind Khorana (born 1922), and others, the details of how DNA specified the genetic code had been broadly worked out.
Proteins are primary components of the cell, providing structural elements,
useful tools, and, in the form of enzymes, protein-based catalytic systems to
support cell reactions. Proteins are chains of "amino acid" subunit
molecules, with 20 different amino acids used in human proteins:
_____________________________________________________
alanine (ala) leucine (leu)
arginine (arg) lysine (lys)
asparagine (asn) methionine (met)
aspartic acid (asp) phenylalanine (phe)
cysteine (cys) proline (pro)
glutamic acid (glu) serine (ser)
glutamine (gln) threonine (thr)
glycine (gly) tryptophan (trp)
histidine (his) tyrosine (tyr)
isoleucine (ile) valine (val)
_____________________________________________________
It was the fact that proteins had 20 different possible subunits that sent
researchers down the wrong track of thinking that proteins were the agents of
heredity, since the four different nucleotide subunits of DNA seemed to be
too limited in number to do the job. This was overlooking the reality,
obvious in hindsight, that groups of several of the four nucleotides could
provide as many variations as needed.
The primary function of DNA is to "code" the production of proteins. The DNA
chain is organized in "triplets" or "codons" of bases, coding a particular
amino acid in a protein chain as follows:
_____________________________________________________________________
ala: GCU GCC GCA GCG leu: UUA UUG CUU CUC CUA CUG
arg: CGU CGC CGA CGG AGA AAG lys: AAA AAG
asn: AAU AAC met: AUG
asp: GAU GAC phe: UUU UUC
cys: UGU UGC pro: CCU CCC CCA CCG
glu: GAA GAG ser: UCU UCC UCA UCG AGU AGC
gln: CAA CAG thr: ACU ACC ACA ACG
gly: GGU GGC GGA GGG trp: UGG
his: CAU CAC tyr: UAU UAC
ile: AAU AUC AUA val: GUU GUC GUA GUG
START AUG
STOP UAG UGA UAA
_____________________________________________________________________
A single DNA strand may encode a number of proteins, with a section encoding
a single protein called a "gene" and marked out by the START and STOP
sequences listed above. The general principle is: "one gene, one protein"
-- though this is a bit of an oversimplification. The entire complement of
genetic information in an organism is known as the "genome".
Protein synthesis involves DNA, enzymes, and a cellular organelle called the "ribosome". Under the control of enzymes, a DNA strand is split in half down the middle, and then replicated with a half-strand of a closely related molecule known as "messenger RNA (mRNA)", which is almost identical to DNA, except that it uses a slightly different sugar molecule, and the nucleotide uracil (U) instead of thymine. This process is known as "transcription", and when it is complete, the DNA half-strand releases the mRNA half-strand.
The mRNA then leaves the cell nucleus and links to a ribosome. The ribosome moves along the mRNA strand, reading a triplet at a time. With each triplet, the ribosome acquires an amino acid that is connected to a short RNA sequence named "transfer RNA (tRNA)", which allows the ribosome to match a specific amino acid to a specific triplet code.
The ribosome strips the tRNA off the amino acid, links the amino acid into the emerging protein chain, and then moves on to the next mRNA triplet. This scheme of protein construction is known as "translation". Later work revealed increasing levels of elaboration to this process, with "regulatory sequences" encoded in DNA working with a system of enzymes to control cell construction and operation.
* FOOTNOTE -- THE RISE & FALL OF LYSENKOISM: Although officials of the Soviet Union liked to proclaim the "scientific" basis of their society and Soviet scientists figured prominently in the list of Nobel prize winners, during the time that modern genetics and evolutionary theory rose in the West, the USSR was going down a bizarre blind alley that would prove a memorial to the triumph of ideology over sense.
In the late 1920s, Trofim Denisovitch Lysenko (1896:1976) was a technician at an agricultural research station in Azerbaijan who came up with the idea of planting a winter crop of peas. It worked, but only because the winter was unusually mild. Lysenko came up with the idea that he might be able to encourage crop plants to grow under winter conditions by simply "conditioning" them to a harsh climate. Essentially, he was resurrecting Lamarckism. As was later observed, he believed that he could get normal crop plants to grow in winter by "giving them a stern talking-to."
The idea was unworkable on the face of it and further efforts along such lines were largely marked by failure. However, Lysenko's initial "success" led to the publication of a flattering article in the state newspaper PRAVDA -- the name was Russian for "Truth", though the paper was not noted for reliable reporting. The article called him the "barefoot professor" and praising his work. The idea that a peasant lad could make major scientific discoveries had a strong appeal to Soviet ideology, and Lysenko quickly grasped that he was on to something. Although he was an incompetent agricultural scientist, Lysenko had an instinct for political propaganda, littering his work with citations from Marx and Lenin, while smearing his enemies as counter-revolutionaries. Soviet ideology also had a built-in bias towards Lamarckism, since it offered the hope of improvement of the people by their own efforts -- while Western genetics implied "genetic determinism", as biological determinism had been recast, which Lysenko denounced as a reactionary and bourgeois concept that implied a static class system. In addition, Lysenko was promising quick results, much quicker than could be obtained by mainstream geneticists through selective breeding. Why waste time in silly experiments with fruitflies?
Crackpots tend to believe that the world is against them, but unlike most crackpots Lysenko could do something about his enemies, since he had the ear of Soviet dictator Josef Stalin. In 1935, Lysenko declared in a speech at the Kremlin: "Both within the scientific world and outside it, a class enemy is always an enemy, even if a scientist." Stalin, who had little feeling for science but was very keen on dealing with class enemies, stood up and applauded: "Bravo, Comrade Lysenko, bravo!"
Later Lysenko would announce: "I do not consider formal Mendelian-Morganist genetics a science" -- and one of his cronies added: "The teaching of genetics must be eliminated from secondary schools." Mainstream geneticists were arrested and sent to the prison camps for "treason" -- Stalin's USSR had a frighteningly broad definition of the term -- and some did not return. Soviet agricultural science went from failure to failure under Lysenko's direction.
Josef Stalin died in 1953 and there were many who hoped that Lysenko's star would then fall, but he was too entrenched. Under the new regime led by Nikita Kruschev, Lysenko would remain in a position of authority, even though Premier Kruschev's son Sergei, a rocket engineer, told his father that Lysenko was a charlatan. Indeed, with Watson and Crick's discovery of the structure and function of DNA, Lysenko was moving on to new heights of crackpottery, announcing that it was "impossible to ascribe an attribute of life, IE heredity, to a nonviable substance, deoxyribonucleic acid, for example." As described by Watson & Crick, the structure and function of DNA left no apparent room for Lysenkoism, and so Lysenko and his cronies had to reject it.
Kruschev was nowhere near as repressive as Stalin, however, and by the time of Kruschev's ouster in 1964, criticisms of Lysenko were increasing in volume among the Soviet scientific community. Physicist Andrei Sakharov, father of the Soviet hydrogen bomb and later a world-famous political dissident, denounced Lysenko to the Soviet Academy of Sciences:
BEGIN QUOTE:
He is responsible for the shameful backwardness of Soviet biology and genetics in particular, for the dissemination of pseudo-scientific views, for adventurism, for the degradation of learning, and for the defamation, firing, arrest, even death of many genuine scientists.
END QUOTE
Kruschev's sacking was, ironically, partly due to the fact that Soviet agriculture had suffered a series of crop failures under his leadership. The crop failures appear to have been due to mismanagement by the clumsy Soviet agricultural system in general, not Lysenko's crackpot ideas in specific -- but he couldn't have helped matters any. A commission of the Academy of Sciences reviewed Lysenko's work and delivered a highly critical report. Lysenko was stripped of his rank and privileges, to live in bitter obscurity until his death.
* DISCOVERING PREHISTORIC HUMANS (2): The discoveries of prehuman fossils by Dubois, Dart, and Broom in the prewar era accelerated in the postwar era, particularly through the work of a white Kenyan named Louis B. Leakey (1903: 1972) and his wife, Mary Leakey (1913:1996). In 1959 the Leakeys discovered another variety of "robust" australopithecine in Kenya, and in 1961 they discovered a very different hominid, which became known as Homo habilus. By this time the consensus was emerging that the australopithecines were a side-branch of human evolution that went extinct; Homo habilus, in contrast, was closer to the main line of human evolution, roughly a predecessor to Homo erectus. It appeared that australopithecines and Homo habilus lived side-by-side.
More discoveries cropped up to bolster these concepts. In the mid-1970s, a surprisingly (if by no means perfectly) complete skeleton of an early australopithecine was discovered in Ethiopia, with the specimen named "Lucy". It confirmed much of what had been believed about the australopithecines, in particular that they walked erect. Louis and Mary Leakey's son Richard Leakey (born 1944) also discovered a number of hominid fossils, in particular helping confirm the past existence of Homo habilus.
Older hominid fossils were discovered in the 1990s that traced the existence of the hominid branch of the primate evolutionary tree farther back in time. There are now hundreds of hominid fossils for australopithecines, Homo habilus, and Homo erectus, and neither their reality nor their testimony to the antiquity and evolution of the human species can be realistically denied any longer. The exact arrangement of the hominid family tree does remain open to debate, and the absence of hard genetic evidence that can't be obtained from such fossils the argument will be difficult to resolve. However, as is true in general for disputes in modern evolutionary biology, this is merely an argument over details.
* KIMURA'S NEUTRAL THEORY: With the development of the modern synthesis and the discovery of the genetic code, evolutionary science entered a new era. The emerging science of what would be called "genomics" promised to give evolutionary biologists a microscope into the organization of organisms and the relationships of species. An American biologist named Richard C. Lewontin (born 1929), a student of Theodosius Dobzhansky, was a pioneer in this effort, using a technique known as "gel electrophoresis" to perform genomic studies. He discovered that the genetic variability even among the same species was much greater than anyone had anticipated.
This discovery meshed neatly with the work of a Japanese population geneticist, Motou Kimura (1924:1994), who in 1968 began to argue that Darwinian evolution was heavily driven by "neutral" mutations that neither harmed nor helped an organism -- they were "selectively equivalent". The idea was not completely new in itself, there was no reason for anyone but a strict selectionist to reject the idea that a species might undergo changes that did neither harm nor good -- but Kimura came up with a detailed model of how it might work, showing how genetic drift could accumulate variability in a species that, when new selection pressures arose, would provide a basis for new adaptations.
Kimura's "neutral theory" was at first interpreted as an attack on Darwinism, but Kimura was careful to point out that it contradicted nothing in Darwin's basic concepts: "The theory does not deny the role of natural selection in determining the course of adaptive evolution." In fact, Darwin himself had briefly mentioned the idea early in chapter four of THE ORIGIN OF THE SPECIES: "Variations neither useful nor injurious would not be affected by natural selection and would be left a fluctuating element ... " Kimura's ideas were a further extension of the earlier work of Sewall Wright, in essence claiming that the movement of the Darwinbot over the fitness landscape was more drunken and unsteady than had been previously assumed. Where Kimura was controversial was in his claim that neutral variation was more important in evolution than natural selection.
Kimura's work focused on neutral variations at the genetic level, suggesting that even if the physical form of organisms didn't change drastically over time, they would continue to acquire genetic variations that could feed evolutionary change in the future. Others suggested that the neutral theory applied at higher levels as well. Harvard paleontologist Steven Jay Gould (1941:2002) criticised the notion that all features of organisms were necessarily purposeful, created by natural selection. Why, for instance, did the famed dinosaur super-predator, the tyrannosaur, have such ridiculously little forearms? They were probably just vestigial and served no major purpose. Many features of organisms, as Gould saw it, were merely accidental, or incidental consequence of adaptations, and provided neither selective advantage nor disadvantage in themselves.
Gould referred to explanations to show how every little feature of an organism was derived from natural selection as "just so" stories, referring back to Rudyard Kipling's fables for children of how the elephant got its snout and so on. Still, although the debate between neutralists such as Gould and strict selectionists -- or "adaptationists" as Gould called them -- got a bit hot at times, the argument was never really over Darwinism itelf.
Nobody denied that Darwinian evolution involved both random variations and selected adaptations, it was just a question of how much weight was put on the two processes. In fact, trying to establish the dividing line between the two was tricky, since neutral variations in organisms could, when conditions changed, provide a basis for new selected adaptations. The argument continues at a subdued level; the contemporary consensus is that Kimura overstated his case, but he was certainly not entirely wrong.
TO BE CONTINUED
* Website additions for the month include:
Updated documents include:
New reviews include:
This last month's online blog entries include items on: railroad infrastructure, Florida road trip, Chinese corpse brides, African micro-hydro, astronaut attitude problems, natural house construction, new San Francisco Bay Bridge, electronic RF sensor networks for conservation, the law and electronic discovery, Ethiopian commodities exchange, RFID introduction delayed, Boeing 787 Dreamliner, third-world economic benefits of cellphones, shady DNA analysis by mail, immobots, and Chick tracts.
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