Recent discoveries led some scientists to a conclusion about need of introduction of amendments and additions in the synthetic theory of evolution.
Kevin Laland inspected a conference room in which several hundreds of people for discussion of the future of evolutionary biology gathered. One of colleagues sat down by him and asked how in his opinion there are affairs in this area.
“It seems to me that everything goes normally — Laland answered. — Serious disputes didn’t arise yet”.
Kevin Laland is an evolutionary biologist from University St Andrews in Scotland. In the cold cloudy November afternoon it arrived to London for the joint organization of a meeting of Royal scientific organization on the subject “New Tendencies in Evolutionary Biology”. In the hall there was a great number of biologists, anthropologists, doctors, the scientists working in the field of computer sciences and the self-proclaimed ideologists. The royal scientific organization is located in the majestic building overlooking Saint-James the Park. The only thing that Laland could make out from highly located conference room windows today, there were construction woods and a front grid for repair work. Inside, as Laland hoped, too upgrade, but already other type will take place today.
In the middle of the 1900th years biologists added the theory of evolution of Darwin with new conclusions from the field of genetics and other fields of science. The so-called “synthetic theory of evolution” which sets already 50 years the direction of evolutionary biology became result of it. At that time scientists learned great variety of the facts about how life is arranged, and can order the whole genomes now, watch how genes in the developing embryos join and switched off and as animals and plants react to changes in the environment.
As a result, Laland and group of the biologists holding one with it the opinion came to a conclusion that the synthetic theory of evolution needs review. There was a need to give it the new form of vision of evolution which they christened the concept of “expanded synthesis”. Other biologists expressed disagreement, having declared insufficiency of the bases for similar shift of a paradigm.
This meeting in Royal scientific organization was the first public conference where Laland and his colleagues had an opportunity to provide the point of view in the matter. But Laland was only not adjusted to preach the views to adherents therefore the outstanding evolutionary biologists who are skeptical about the principles of expanded synthesis were also invited to a conference.
Both parties stated the points of view and critical remarks in a civilized manner, but sometimes in the hall tension expressed by clatter, rolling of eyes and a poor applause hung.
But didn’t reach fights. At least now.
Evolution as usual
For any science there comes time of transformations and time when affairs take its course. After Galilei and Newton in the 1600th years pulled out physics from captivity of old delusions, it began to move forward from one modest achievement to another up to the 1900th years. Then Einstein and other scientists laid the foundation of quantum physics, submitted the theory of relativity and other new ways of knowledge of the Universe. Any of them didn’t claim that Newton was wrong. But it becomes clear that the Universe actually is not only substance in the movement.
In evolutionary biology there were own revolutions. The first, certainly, began in 1859 with Charles Darwin’s book “Origin of species”. Darwin united to data from the field of paleontology, a fetology and other sciences to show the general parentage of all live organisms. It also entered a concept of natural selection — the mechanism for management of these long-term changes. Each generation of a look had big variability. Sometimes she helped organisms to survive and breed, and, thanks to heredity, was given to the next generations.
Darwin inspired biologists of the whole world to studying of animals and plants from the new point of view, interpreting their biology as the adaptations which arose in the previous generations. And he succeeded in it in spite of the fact that he had no the slightest concept about genes. Only in the 1930th years of genetics and biologists combined the efforts and reformulated the evolutionary theory. Heredity began to be considered as transfer of genes from generation to generation. Changes happened owing to mutations which could mix up for creation of new combinations. New types arose when in populations mutations which made interspecific crossing impossible were formed.
In 1942 the British biologist Julian Huxley described this activly formed concept in the book “Evolution: modern synthesis”. Scientists still use this name. (Sometimes they call it neodarvinism though this term is actually wrong. The term “neodarvinism” was entered in the 1800th years and was used by the biologists advancing Darwin ideas at his life).
The synthetic theory of evolution was the potent tool in the sphere of the questions bound to the nature. Scientists used it for a number of opening about a life story, having answered, for example, a question why some people are inclined to genetic diseases like drepanocytic anemia or why pesticides cease to affect wreckers sooner or later. But already soon after formation of a concept of modern synthesis various biologists began to complain of its excessive categoriality periodically. However only in the last several years Laland and other scientists managed to unite and coordinate efforts for development of the principles of expanded evolutionary synthesis which could succeed it.
Researchers don’t consider the synthetic theory of evolution a wrong concept — just it isn’t capable to display all richness of evolution. Organisms inherit more, than just genes — they can inherit also other cellular molecules, and also behavior to which they study, and the habitat changed by their ancestors. Laland and his colleagues also challenge the predominating role of natural selection in an explanation of how after all life became such what we know her now. Other processes, starting with rules by which types, to external conditions of their dwelling develop also can influence the course of evolution.
“It isn’t to fasten more and more mechanisms to what is already available — Laland has told. — It is necessary to look at relationship of cause and effect from a different angle”.
The biologist of Tel Aviv University Eve Yablonka in the speech has tried to analyse proofs that not only genes can cause heredity forms.
Our cages use a number of molecules to distinguish what of genes produce proteins. For example, during process under the name “methylation”, cages limit the DNA for preservation of certain genes closed. When cages share, they can use the same principle, controlling, thus, new DNA. The certain signals received from the environment can force cages to change so-called “epigenetic” control, allowing organisms to adapt to new conditions.
Some researches show that under certain circumstances epigenetic changes at a parental individual can be transferred to descendants. And they, in turn, can give this changed epigenetic code to the children. It is one of types of inheritance out of genes.
This principle of inheritance is especially accurately traced at plants. In one of researches scientists could trace the changed scheme of methylation to 31 generations on the example of a plant under the name Arabidopsis rezukhovidka. Such type of inheritance can change functioning of an organism considerably. During other research scientists have found out that the inherited schemes of methylation could change time of blossoming of Arabidopsis and influence the size of his roots. The variability caused by these schemes was more than that that is caused by usual mutations.
Having produced the evidence, madam Yablonka gave arguments that epigenetic distinctions could determine a maturity of organisms for production of posterity. “Natural selection could exert impact on this system” — she declared.
As natural selection exerts considerable impact on the evolution course, conferees provided proofs of how it can be limited or displaced in other direction. The biologist of the Vienna University Gerd Müller gave an example from an own research on lizards. Some types of lizards during evolution lost fingers on hinder legs. One types had only four fingers, at others only one, and some lost extremities entirely.
According to Müller, the synthetic theory of evolution forces scientists to look at these mechanisms only as on result of natural selection which favors to some one option thanks to its benefits in survival. But this approach won’t work if you ask a question, in what a benefit to a certain type of individuals in loss of the first and last fingers, but not any other.
“The answer to this question consists in lack of a real selective benefit” — Müller told.
The key to understanding of why lizards lose certain fingers on paws, first of all is in how fingers of lizards develop in an embryonic condition. At first on each side shoots appear, and then from them five fingers, always in the same sequence develop. And they lose them during evolution already upside-down. Müller assumes that such restrictions are caused by inability of mutations to reproduce all possible changes of a sign. Some combinations of fingers, thus, become unavailable, and natural selection won’t be able to choose them in general.
Development can limit evolution, and on the other hand allocates animals and plants with high plasticity. The evolutionary ecologist of Wesleyan University Sonia Sultan in the speech gave a curious example, having told about the plant of family of buckwheat studied by it — the mountaineer peppery.
Within modern synthesis, Sultan declared, adaptation of the mountaineer peppery will seem you precisely verified result of natural selection. If it grows in conditions of insufficient lighting, natural selection will favor to plants with the changed signs allowing them to expand violently in this environment by, for example, development of wider leaves for photosynthesis. And at those that grow in case of a bright sunlight adaptations for successful growth in other conditions develop.
“It speaks well for that point of view to which opposition our meeting is devoted” — Sultan told.
If you grow up genetically identical sprouts of the mountaineer peppery in various conditions, finally you receive the plants belonging as though to different types.
Let’s begin with the fact that the mountaineer peppery adjusts the size of the leaves to quantity of the received sunlight. In case of bright light their leaves become narrow and thick, and in case of insufficient lighting — wide and thin. In the dry soil these plants take root deeply to the earth in search of water, and in well humidified roots become short, volosovidny and superficial.
Scientists at a meeting claimed that similar plasticity can promote the evolution course in itself. It, for example, allows plants to extend in various habitats for which natural selection then adapts their genes. Among speakers there was Susan Enton, палеоантрополог from the New York university which declared that plasticity can play a significant role and in the evolution of the person underestimated still. All because in the last half a century modern synthesis significantly influenced its studying.
Paleoanthropology were inclined to treat the features found in fossils as to result of genetic distinctions. It allowed them to recreate an evolutionary tree of the person and relatives to it the died-out forms. Adherents of this approach achieved powerful results, Enton recognized. By 1980th years scientists found out that about two million years ago our early relatives were small growth and possessed a small brain. Then representatives of one of lines of descent became higher growth and developed a big brain. This transition marked an origin of our sort, Homo.
But sometimes a paleoanthropology found variations which sense was difficult to be understood. Two fossils could seem belonging to one type on one signs, but differ strongly on others. Scientists, as a rule, ignore such distinctions caused by the environment. “We wanted to get rid of all this and to pass to an essence” — Enton told.
But there is too much “all this” that he could be ignored. Scientists have found a tremendous variety of the humanoid fossils dated by the period between 1,5 and 2,5 million years ago. High, and some some don’t have some of individuals, a big brain, and at some small. All their skeletons have lines of a type of Homo, but at everyone the confusing combined divergences are observed.
Enton considers that the principles of expanded synthesis can help scientists to understand this complicated story. She, in particular, considers that her colleagues have to seriously treats plasticity as to an explanation of a strange variety of early fossils of the person.
In support of this idea Enton has noted that living people possess own type of plasticity. Quality of food which the woman receives during pregnancy can influence growth and health of the child, and influence it can be traced up to his majority. Moreover, the sizes of the woman which partly depend on a diet of her own mother can affect her children. Biologists have found out, for example, that children of women with long legs, as a rule, above peers.
Enton has assumed that strange changes from paleontologic archive can is even more drama examples of plasticity. All these fossils belong by then when the climate of Africa underwent the strongest fluctuations. Droughts and plentiful rains could change food resources in different regions of the world therefore early people would begin to develop in other direction.
The theory of expanded evolutionary synthesis can also help to deal with one more chapter of our history — emergence of agriculture. In Asia, Africa and both America people have cultivated grain crops and the cattle. The archeologist from Smithsonian Institute Melinda Zeder has made the report on problematical character of understanding of how this transformation could happen.
Before people have begun to go in for agriculture, him itself had to get food and to hunt a game. Zeder has explained how many scientists treat behavior of collectors in the context of modern evolutionary synthesis: as something excellently adjusted by natural selection for receiving the best remuneration for the efforts in search of food.
It is difficult to present how such collectors in general could pass to agriculture. “You don’t derive immediate pleasure that you grab food and put it in a mouth” — has told me Zeder.
Some scientists have assumed that transition to agriculture could happen during change of climate when search of wild plants became much more difficult. But Zeder and other researchers haven’t found in general any proofs of crisis at which there could be agriculture.
Zeder claims that there is also other point of view in this respect. People are not the obedient zombies trying to survive in the constant environment, and creatively clever persons capable to change the environment and to direct evolution in the new direction.
Scientists call it construction of an ecological niche — process in which many types are involved. Among classical cases it is necessary to mark out beavers. They bring down trees and build a dam, creating a pond. In these new conditions it will be better for one species of plants and animals, than others. And they will adapt in a new way to the environment. It is right not only for the plants and animals living around a beaver pond but also for beavers.
By recognition Zeder, her first acquaintance to a concept of construction of an ecological niche became for it a revelation. “It was similar to small explosions in my head”, she has told me. The archeological finds collected by her and other scientists will help to understand how people managed to change environment conditions.
Early collectors, on all signs, have moved wild-growing plants away from their natural areas always to have them near at hand. Watering plants and protecting them from herbivores, people have helped them to adapt to the new environment. Weed types have also replaced the habitat and became independent crops. Some animals have also adapted to the environment, having become dogs, cats and other house types.
Gradually from chaotically scattered plots of land occupied by wild plants, conditions of the environment were replaced with densely located arable fields. It promoted not only evolution of plants, but also cultural development among peasants. Instead of wanderings all over the world like nomads they were proved in villages and have had an opportunity to process the earth around. Society became stabler as children came into an ecological fortune from the parents. The civilization has so begun.
Construction of an ecological niche is only one of a set of concepts of the theory of expanded evolutionary synthesis which can help to understand domestication process, has told Zeder. During the speech, it a slide behind a slide has submitted various forecasts, since movements of early collectors to rates of evolution of plants.
“It seemed that it is the commercial about the principles of expanded evolutionary synthesis — has told me then, laughing, Zeder. — But there is more to come! You can receive a set of kitchen knives!”
Return of natural selection
Among attendees in the hall there was a biologist by the name of David Shaker, the researcher from university St Andrews. He quietly listened to discussions for one and a half days, and now decided to take the floor and raised a hand.
Denis Nobl, the physiologist with a shock of a gray hair and in a blue jacket was the speaker addressing it. Nobl who carried out the most part of the career in Oxford told that it began as the traditional biologist considering genes the final reason of all real in an organism. But in recent years he changed the opinion and began to speak about a genome not as about a basis for life, but as about the sensitive body revealing a stress and capable to be reconstructed for overcoming problems. “I needed a lot of time to come to this conclusion” — Nobl told.
To illustrate this new view, Nobl told about a variety of recent experiments. One of them was published last year by staff of University of Reading and consisted in a research of bacteria which move in the environment by means of the long rotating tails.
First of all, scientists allocated the gene responsible for tail otrashchivaniye from DNA of bacteria. Then they placed the received tailless individuals in Petri’s cup with a poor inventory of food which those shortly absorbed. Without an opportunity to move they died. Less than in four days of stay in these awful conditions, bacteria started over again swimming. After careful survey it was found out that they grew themselves new tails.
“Strategy consists in creation the bystrykh of evolutionary changes of a genome in response to adverse external effect — Nobl explained to audience. — It is self-sustaining system which gives the chance of manifestation of certain properties irrespective of DNA”.
It didn’t seem to Shaker convincing and after an applause abated, he decided to get with Nobl into an argument.
“You couldn’t comment on operation of the mechanism which is the cornerstone of this opening?” — Shaker asked.
Nobl began to falter. “The mechanism in general, I can and …” — he told, and then began to speak about networks and rules and feverish search of recovery from the crisis. “You need to address the source text of the report” — he declared then.
While Nobl very much tried to answer, Shaker looked at the report opened in his pad. Also began to read one of paragraphs loudly.
“Results of our operation show that natural selection can quickly change regulatory networks — Shaker read and postponed an iPad. — It fine, just remarkable example of bystry neo-Darvinian evolution” — he declared.
Shaker derived the essence of feelings of considerable number of sceptics to which I managed to talk at a conference. The ambitious rhetoric about paradigm shift, mostly, was groundless, they said. However these sceptics didn’t remain in the shadow. Some of them decided to take the floor personally.
“I think, expect the speech about evolution of the Jurassic Period from me” — told, having risen by a tribune, Douglas Futuyma. Futuyma is a sladkorechivy biologist of the Hundred-uni university – Brook in New York and the author of the main textbook on evolution. During the meeting it was filled up with complaints that in textbooks not enough attention is paid to such things as epigenetics and plasticity. In effect, Futuyma just for this purpose was also invited to explain to colleagues why these concepts were ignored.
“We shall recognize that the basic principles of the synthetic theory of evolution are strong and justified” — Futuyma reported. Not only it, he added, but also and the varieties of biology discussed in Royal scientific organization are actually not so new. Creators of the synthetic theory of evolution mentioned them more than 50 years ago. For their understanding the set of the researches relying on the modern evolutionary synthesis was conducted.
Let’s take plasticity. Genetic variations in animals or plants regulate the range of forms in which the organism can develop. Mutations are able to change this range. And mathematical models of natural selection show how it can promote one types of plasticity at the expense of others.
If the theory of expanded evolutionary synthesis is necessary to nobody how quitted what devoted it the whole meeting in Royal scientific organization? Futuyma assumed that this interest was rather emotional, than scientific. Its principles made life driving force, but not sleeping mutation tool.
“I think for science what we read emotionally or esthetically more attractive can’t be the base” — Futuyma declared.
And nevertheless he made every effort to show that researches about which it was told at a meeting can lead to some interesting outputs about evolution. But these outputs can result only from hard work which involves appearance of reliable data. “On this subject enough sketches and reports are written” — he told.
Some members of audience have begun to altercate with Futuyma. Other skeptically adjusted speakers were enraged by arguments which as they thought, don’t make sense. But the meeting after all managed to be finished for the third day without any fights.
“It is probably the first of many and many meetings” — Laland has told me. In September the consortium of scientists in Europe and the USA has received financing of 11 million dollars (from them 8 million from John Templton’s Fund) for carrying out 22 researches devoted to the principles of expanded evolutionary synthesis.
Many of these researches will check forecasts which have resulted from the synthetic theory of evolution over the past few years. They, for example, learn whether types which build own habitat — webs can, hornet’s nests etc. — to develop into bigger quantity of types, than those which don’t do it. They will also consider a question of whether high plasticity in new conditions allows to adapt quicker.
“Carrying out these researches is about what our critics ask — Laland has told. — Go and find proofs”.