36. Evolution in the United States 1920-1930

While the battle for the meaning of holism and the outer side of life was being fought in Africa, the Americans and especially TH Morgan, were busy experimenting with clearer inner objectives. Mutations of all shapes and sizes were being selected and bred in a small range of laboratory-bred organisms such as fruit flies, which were much easier to use in experiments than guinea pigs or peas.

200px-Thomas_Hunt_Morgan    200px-Drosophila_in_the_lab

By about 1920 Morgan and his group of geneticists in New York had made some important discoveries about basic biology. They had proved that genes line up in single rows on the chromosomes inside the cell, and were arranged in a definite order that changed for each individual of a single species. But what didn’t change were the particular features of each gene on the chromosomes. The group also came to think that the genes worked by controlling a chemical system of great complexity, sensitive to the changing conditions outside and regulating all the development and chemical work inside.

However, America was also the breeding ground for an alternative theory that would have an impact on the science of life. In the early 1920s, only sixty years after the American Civil War, the Creationist movement began to make great strides in the South.

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Up in Canada, William Bateson had been lecturing on tour, trying to gain support for his non-particulate system of heredity that somehow involved physical vibrations. So different to Morgan’s theory, his words were music to the ears of the right-wing religious fundamentalists: “Less and less was heard about evolution in genetical circles, and now the topic is dropped. When students of other sciences ask us what is currently believed about the origin of species we have no clear answer to give. Faith has given place to agnosticism.” Bateson didn’t realise the strength of feeling about the impact of Darwin’s Origin on the value of Genesis that still existed in America.

th-8 trial lawyers Darrow & Bryan   th-9  John Scopes

Three years later a criminal trial on the matter attracted so much attention that it was broadcast on national radio. A biology teacher in Tennessee called John Scopes was proud to explain to his students how natural selection played a role in building up biodiversity, and that there were still a lot of unanswered questions.

220px-American_Civil_Liberties_Union_logo – even defends those who burn the flag –   160px-WCWProtest_WashingtonDC-1

He was supported by the American Civil Liberties Union to say that he taught these ideas of Charles Darwin intentionally, in the face of eager opposition from the World Christian Fundamentals Association. Scopes was found guilty and fined a hundred dollars but was acquitted by a legal technicality on appeal.

As was pointed out at the trial, there seemed to be no obvious way by which the mechanisms attributed to Darwin and Mendel could come together into a single theory. Even when Dobzhansky began work in New York in 1927 no-one expected fruit fly genetics to fit with any of the theories of evolution that were available to them. Morgan, their leader, even said that “genetics can be studied without any reference to evolution.” In reaction to this mood, Dobzhansky worked on the idea that evolution was about how species split up, how they were discontinuous. He had to explain how the continuous change in natural populations also explained the whole assortment of taxonomic diversity and that was still an impossible task.

In the national spirit of getting things done, hard-graft experimental work went on in the biology laboratories of the United States, starting in Manhattan with a group that some other biologists called the New York Mafia. One of the first was Hermann Muller (1890-1967) who was brought up in Harlem, founded a science club at his high-school and loved summers in the country.

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In 1910 he joined the students studying genetics at Morgan’s fly room at Columbia University and investigated some of the things that the linked genes of the fruit fly Drosophila had in common. He found evidence for the theory that bits of chromosomes broke off and crossed over to the other pair, in a different order. It meant that genes were stable units of inheritance and somehow passed the information from one generation to another on the chromosomes. Miller produced mutations of single genes and of larger parts of the chromosomes from X-radiation, opening up the possibility of measuring the effects of this genetic change. In the 1930s he left New York and spent good lengths of time working in Europe and the Soviet Union, enjoying the power that his newly awarded Nobel Prize had given him.

Another Drosophila geneticist settled in New York in the 1930s, pleased to be away from Hitler’s Germany. This was Richard Goldschmidt who first saw a sudden and quick change in the size of some fruit flies’ body parts, and was surprised that they were inherited by future generations as permanent characters. He called these unfortunate flies “hopeful monsters” but couldn’t prove why or how they came about, other than to say they were mutations that had happened within one generation.

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Goldschmidt’s 1940 book The Material Basis of Evolution proposed a new system of life: ‘evolution in single large steps on the basis of shifts in embryonic processes produced by one mutation.’ As an example he showed that the breed of bow-legged dogs, the dachshunds, were initially dismissed as monsters and were later cultivated to extract badgers from dens. He had other examples: gypsy moths with limbs on the wrong body segments; flatfish with both eyes routinely occurring on one side of the head; the joining of a bird’s tail vertebrae to form a fan-like arrangement of feathers. Because they didn’t fit in with any other kinds of mutant or inherited traits that were known at the time, Goldschmidt’s monsters were no more than text-book anomalies that most students jokingly dismissed. (About 70 years later Ed Lewis’s Nobel Prize was based on worked that revived their importance and explained their occurrence.)

Initially no one took Goldschmidt seriously in America. Only now has he become an important scientist for the value he attached to the role of mutation in evolution, and he is fast becoming known as the father of a new multidisciplinary group interested in evolutionary development. In his theory, mutations occur within a single generation, and the altered creatures that survive follow the pattern of Mendel’s predicted ratios of inheritance. Modifications that happen in this way can become permanent features of the new species and manifest themselves on large and small scales.

th-3 Rothschild at Tring   th-5  Mayr at home

Another of the New York group was Ernst Mayr, a very different character with a similar background to Goldschmidt, and who was appointed in 1931 as a curator of birds at the American Museum of Natural History. The museum had just purchased a large collection of bird skins from the banker Walter Rothschild, with whom Mayr had worked in England. Rothschild was both a collector and a benefactor and pressed Mayr’s supporters that his appointment would benefit the growth of ornithology in New York. As a teenager in Northern Bavaria Mayr loved bird-watching and impressed the local experts by reporting the first Red-Crested Pochard to be spotted in the region since 1845. For that his mother gave him his treasured pair of binoculars and he was invited to do voluntary work at the local museum: “It was as if someone had given me the key to heaven”.

Rothschild met him again in 1927 at the International Zoological Congress and invited him to take part in an expedition to New Guinea where he proved himself to be a gifted observer and a successful collector. Back in Germany with some of his most choice specimens from the trip, he described 26 new species of birds and 38 orchids. The work made him think seriously about the scientific value of what he was doing, for although the challenge of making a new species had been faced millions of times by almost as many people, no-one was very sure about what a species actually was. It was Mayr who then clarified the matter by insisting that a species was a group that could breed among themselves and with no others: it was not just a question of likeness.

Just a few blocks away from the museum at Columbia University was Theo Dobhzansky, the all-round Russian biologist who also decided to stay on in New York. In 1937 he summarised the importance of experimental genetics to the evolution of species in Genetics and the Origin of Species. This gathered all the empirical evidence available from that area and found it corroborated the mathematical framework set by people like Wright and Haldane. Although Dobhzansky hadn’t understood the mathematics, his conclusions were the same: that Mendel’s genetic recombinations could lead to evolution by natural selection. The book also extended the influence of Mendel on Darwin beyond where the maths had reached by saying more about the concept of species.

Dobhzansky’s fears of mathematics were balanced by his ease of understanding for Sewall Wright’s fitness landscapes, showing that when populations of the same species become isolated they adapt to any slightly different conditions they encounter. As an example Wright compared populations from the same species at the tops of neighbouring mountains and found slight differences. With this, Dobhzansky became confident enough to understand his neighbour Sewall Wright and argue across the Atlantic with Haldane and Fisher about their previously mysterious mathematics.  

There, also, HG Wells had his own views about these matters and he shared some with Julian Huxley in 1928. “My last talk with Bateson was in N.Y. and he has a schoolboy pleasure in making trouble and a Samuel Butler-like hatred for Darwin. Any fool can play the negative game and no doubt some of the young fools will go on with it.” Huxley pointed out that in his early work Bateson had over-rated large mutations as cause of immediate evolutionary change, but eventually came to accept Darwin’s position of slow genetic combinations, including occasional mutations.

200px-Theodosius_Dobzhansky,   It was at this confused time in history that Theodosius Dobzhansky had begun his career in Russia where experimental Mendelian genetics was merged with traditional taxonomy and natural history. He had become a specialist in ladybird beetles as well as a skilled Drosophila experimentalist. In New York, these were two separate and largely hostile worlds, not even able to agree about what it was that was evolving. Was it a group, a species or an even larger grouping, or maybe something smaller like an individual or a cell or something more microscopic? Dobzhansky noticed regional varieties of the flies had more genetical similarity with one another than with flies from elsewhere. Once again it was becoming clear that as well as searching inwards for the smallest unit of inheritance it was also necessary to look outside the organism into the environment to find some kind of trigger. And the complex detail that was involved in both directions turned out to be vast. Clearly, there was still a need for the influence of an holistic multi-disciplinary outlook.

This was a frustration feared by the few surviving great Victorian polymaths, realising that their kind would not survive in the new age of so much specialist detail. Even the first hopeful signs that appeared for biology in Russia after the revolution were short-lived. Back in 1917 Lankester saw it as “a new spring of time” but within ten years was told by his friend Wells that Lenin, the “dreamer in the Kremlin” had little more than an emergency government. In 1926, two years before he died Lankester sent a post card to Wells, one from the Natural History Museum with the picture of a huge carnivorous dinosaur on one side and on the other: “an ancestor of the Bolsheviks”. Dobzhansky was not the only biologist to have agreed.

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