Six news items on human evolution

A step toward a resurrected Neanderthal? Remember the idea played out in "Jurassic Park"? To extract DNA from fossils, read it, and introduce it into the egg cell of a modern animal? As regards dinosaurs, such an idea is undoubtedly pure fantasy. Of course, a complete restoration of the DNA of extinct reptiles is impossible. Of course, besides DNA sequences, to restore a vanished species one must have a suitable egg cell containing a highly ordered complex of proteins and other compounds that determine what in the genome of the cell will be read and how it will be embodied during development. Of course, the complexity of such an egg cell is astonishing, and to obtain it and develop it one needs a female of the very species that requires restoration… With close relatives of modern species it is at least clear where to get the egg cell. To restore a mammoth one might try an elephant's egg cell, to recreate the woolly rhinoceros one might use modern rhinoceroses, and to revive a Neanderthal one might take the egg cell of Homo sapiens. But whose egg cell should be used for a dinosaur? A crocodile's? An ostrich's? Alas, such a venture is doomed to failure. Yet even the restoration of DNA sequences is not such a simple matter as it seems at first glance. Recently a report passed through the news agencies about the restoration of a single dinosaur gene. In fact it was a matter of recreating the hypothetical ancestral sequence of one of the proteins in the common ancestor of crocodiles, birds, and dinosaurs. Such work is carried out on the basis of a rather dubious assumption that protein sequences always evolve by the most economical path (with the minimal number of changes necessary to pass from one state to another). Obviously, by such a method nothing definite can be said about the specific features of dinosaur DNA. And yet this concerns only the sequence of a single gene common to dinosaurs and their modern relatives — let alone the genome as a whole! The reading (rather than the abstract reconstruction) of DNA sequences is possible only for recently extinct species. But here too a serious problem is concealed. The DNA of fossil bones is inevitably contaminated with foreign DNA, above all the DNA of bacteria. To identify one species or another, or to compare the degree of kinship, one can use characteristic sequences of mitochondrial DNA (bacteria, as prokaryotic organisms, have no mitochondria). But how is one to recognize the sequences of the nuclear genome of the species being restored, picking out their fragments from a chaos of diverse origin? Specialists of the Joint Genome Institute in California recently announced the reconstruction of the DNA sequence of the cave bear, Ursus spelaeus, extracted from this animal's fossil teeth. The cave bear was a large herbivore that lived alongside ancient humans and served as an object of their hunting. About 10 thousand years ago this species went extinct. Probably the cause of extinction was the change of climate at the end of the Ice Age, but the activity of ancient people also played its part in this event. People not only hunted the cave bear but also worshipped it. At a Neanderthal site in Switzerland, bear skulls have been found neatly arranged in "cupboards" of stone. Continuing the glorious tradition, American researchers used the cave bear's bones for a far more refined sort of sorcery. The extraction and decoding of DNA sequences from the fossil teeth were only the first step of their work. Next it was necessary to identify and exclude the fragments belonging to bacteria, and to isolate the regions of bear DNA (by the way, the cave bear's sequences were identified by comparing them with the sequences of dogs, which belong to the same order Carnivora that includes bears. Unfortunately, the sequences of modern bears have not yet received a detailed study — the extinct species proved more interesting than the living one). A complete sequence of the cave bear's genome was of course not obtained in the end. The result of the work rather demonstrates the effectiveness of the new method of reconstruction, which in itself is already a great deal. And the talk of reviving a Neanderthal is, after all, an advertising stunt rather than a real possibility. Even the cloning of a human being using fully functional cells and a working hereditary apparatus runs into enormous difficulties, to say nothing of the success of transplanting a "fossil" sequence of another species. But hope dies last. An age of change Is it by chance that humans appeared on Earth precisely when it was "set ablaze"? Throughout the preceding tens of millions of years our planet was rather warm. Then Antarctica took up its present position near the South Pole, and the Earth cooled somewhat. But the regular alternation of glaciations, caused by the joining of South and North America, began 3–4 million years ago, in precisely that period when, according to assumption, humans appeared. Specialists from the University of Potsdam studied the deposits of lakes that existed in East Africa (where our ancestors lived) from 1 to 3 million years ago, and discovered that humankind developed in a rapidly changing environment. The diatoms that inhabited the lakes helped in this; their silica skeletons are well preserved in the fossil state. The scientists determined the age of the deposits by the layers of volcanic ash. Of late it has become clear that in stable ecosystems usually only slow evolutionary changes take place, connected with the mutual adjustment of neighbouring species. An age of change is another matter. Even if our ancestors migrated now north, now south, remaining in relatively familiar climatic conditions, they still had to adapt to a continuously changing environment. Our lineage took the path of flexible adaptation to diverse conditions, based on cultural inheritance, and it was precisely the "climatic fever" that promoted such a choice. What next? The biological evolution of Homo sapiens has slowed, and now we adapt to the environment mainly through culture. But rapid changes, including those caused by our own hands, affect other species. For example, the adaptive potential of grey rats is not inferior to the human one. These rodents manage to rebuild their behaviour no matter how rapidly the surrounding conditions change. They have little brain, of course, but they will yet spoil our blood. And who can say which other species, in the nearest evolutionary perspective, will respond to the challenge of the age of change? Halfway to the superhuman Bruce Lahn of the University of Chicago reported in the journal Science that the biological evolution of the human brain continues even in our time. The group of researchers he led studied the spread of two genes, the disruption of whose function leads to microcephaly (a sharp reduction in brain size). It turned out that in healthy people different alleles (states) of these genes occur. The assumption that these alleles are functionally identical is refuted by the fact that in their distribution among the population of our planet traces of the action of selection are observed. The older alleles of the described genes occur more frequently in Africa, but with the dispersal of humankind the frequencies of evolutionarily younger alleles in populations grew. The genes in question evolved more intensively in the ancestors of humans than in related groups of mammals. One may suppose that their normal functioning not only protects against microcephaly but also promotes a better development of the brain in healthy individuals. So, is the brain of native Europeans, Asians, and Americans "smarter" than the brain of native Africans? Lahn's conclusions contradict the established notion that approximately 50–100 thousand years ago the directed biological evolution of our species ceased. Since then the success or failure of an individual, it is believed, has come to be determined not so much by innate endowments as by what the individual has learned. According to traditional views, selection of late has had a predominantly negative character, weeding out the unviable or those "deaf to learning" rather than giving an advantage to the highly adaptive or the highly intelligent. The view presented has an important political consequence. If human evolution ended long ago, there are no grounds for attaching fundamental significance to differences between races that formed later than this date. Here the following logic operates: if we point to the existence of some differences between certain groups of people (representatives of different races, men and women, brunettes and blondes, and so on), someone will conclude that one of these groups is better than another. Such a conclusion may lead to actions not sanctioned in a free democratic society, and the responsibility for these actions must be borne by the researchers who dared to compare. Hence there should be no differences between different groups of people at all, and research aimed at finding them is immoral. Unfortunately, this is not a joke. Feminist communities publish many-page works in which they argue that there are no biological differences whatsoever between men and women¹, while Hollywood producers see to it that, in on-screen reality, not all representatives of one or another national minority turn out to be negative characters. Of course, on an impartial examination the problem turns out to be resolved. The relation "better–worse" is derived from the relation "good–bad", which is applicable only to situations of moral choice. And what moral choice can there be in the fact that character A was born a woman, able to bear children and nurse them at the breast, while character B was born a man and will never become a mother? The situation grows more complicated when we move from comparing the sexes to comparing races, as in Lahn's work. For all the complexity of sexual relations, men cannot yet do without women, nor women without men. Evolution has stitched into most of us a mechanism of interest in and attraction toward the opposite sex. Alas, with respect to representatives of other races what is biologically provided for is rather xenophobia. It is bad when that toward which primitive group egoism pushes is reinforced by rational arguments. "Scientific" explanations of racism have done humankind considerable harm and undermine the authority of the corresponding branches of anthropology. Probably one should block not scientific research from which false conclusions can be drawn, but precisely those conclusions. But in any case the results of such research must be well substantiated. And with respect to Lahn's conclusions a number of questions hang in the air. Selection has been registered for two genes that affect the brain. Does this mean that the selection is connected precisely with the perfecting of brain formation, and not, say, with resistance to infectious diseases? Let us give an example. In green frogs two types of colouration occur: with a stripe along the spine and without it (striata). Their development is determined by a single gene. An analysis of the frequencies of the two colourations shows that their ratio in the population changes over the course of the year. The point is that one of them is more cold-resistant and better tolerates cold winters, while the other is more resistant to toxins and survives better in polluted water bodies. An observer who decided that the selection was directed at the presence or absence of a stripe on the back would make a serious mistake. Returning to Lahn's work, let us note that it lacks data on brain development in the carriers of one allele or another, which are necessary for the interpretation of the results obtained. Perhaps these data are being collected… well, let us wait. And while there are none, let us ask ourselves: can we hope that different groups of people will indeed turn out to be identical in those traits that we consider essential? And if such a hope seems illusory, it is worth thinking about how to make sure that knowledge of our nature and the description of our differences do not become a pretext for elevating some and humiliating others. It is good, after all, that we are different!1 Including in the working of the brain. And this, of course, is not so: recently the British Journal of Psychology, for example, published an article by scientists from the Universities of Ulster and Manchester who showed that men have a reliably higher IQ. By the way, this may be partly explained by the roughly 10% greater volume of the brain in men than in women (though one should not forget that IQ tests are far from an ideal measure of intelligence). Returning to the text Bipedalism — a bug? In recent decades the picture of the main stages of human origins has expanded considerably. A multitude of new finds has made it possible to describe several species of mammals close to humans, as well as a whole series of more distant relatives of ours — representatives of the family of hominids. Earlier notions of the relatively linear character of evolution "from apes into people" proved untenable. Our group developed as much of a "bush" as many others. Not a few of the features that intensified in the course of the formation of Homo sapiens were connected with positive feedback, so that one cannot even say which of them is the cause and which the effect. Into a single knot were woven a complex social organization, flexible behaviour, a prolonged childhood, the enlargement of the brain, cultural inheritance, the transition to permanent sexuality and concealed ovulation, and so on. But what set this process in motion? Perhaps the transition to bipedalism played its part. Earlier it was linked with the mastering of open spaces, into which the former forest dwellers — our ancestors — emerged.

Supposedly, on open terrain one had to straighten up in order to see danger in advance. Finds of bipedal forest primates refuted this hypothesis. A generally accepted explanation of the causes of bipedalism does not yet exist. And one more touch. A five-year-old macaque named Natasha from a safari park near Tel Aviv caught a viral infection that affects the gastrointestinal tract, and nearly died. Having recovered, she switched to bipedal walking, sharply unlike the mode of locomotion of her relatives. Witnesses emphasize the "human" character of Natasha's movement. The clinic's veterinarian, who drew attention to this fact, connects it with damage to the brain as a consequence of the illness. Locomotion is an extraordinarily complex task. A human being does not even stand at all the way that, say, a table stands. Our "immobility" is a continuous sequence of deviations from a certain average posture and their immediate correction. This requires a good development of specialized neural networks in the brain. If the story with Natasha is true, then even apes far removed from humans have everything necessary for bipedalism: from the locomotor apparatus to the system of motion control. Perhaps a disruption of the main controlling mechanism activated the backup one? Then it turns out that the impetus for the birth of civilization could have been given by an error? And what other of our features arose as a consequence of the failure of normal regulatory mechanisms? The continuation of politics by other means, or?.. At many of the social features inherent in humans, representatives of the social sciences and natural scientists look in fundamentally different ways. For the naturalists, characteristic is an analysis of the forms of human behaviour and of its social structures that traces the history of their emergence. Adepts of the "anti-natural" disciplines usually try to give social phenomena a social explanation. For example, the existence of leaders in society can be explained on the basis of some metamorphoses of social-contract theory, or by studying the characteristic features of leaders among baboons.

The moral principles of modern humans can be referred to some tablets of the law, or to the natural morality of animals discovered by the Austrian biologist Konrad Lorenz. What form of behaviour can be recognized as more human than war? Recall at least the role that war played in technological progress or in the evolution of state institutions… However, the roots of this phenomenon can be traced into our distant evolutionary past as well. Thus, new research on this phenomenon was conducted by a Mexican-British scientific team that studied the behaviour of spider monkeys in Mexico. The researchers observed two troops of monkeys that occupied neighbouring plots in the tropical forest. Sorties by members of both troops into the opponents' territory were recorded, organized in practically the same way as among human tribes untouched by civilization. A group of males secretly penetrates into hostile territory, where it seeks out individuals that have become separated from the alien troop, and attacks them. Fatal cases among spider monkeys have not yet been observed, but by analogy with chimpanzees and humans one may suppose that they are quite possible. In the choice of victims in the monkey wars the principles of natural morality (in Lorenz's sense) are manifested. Suffering falls predominantly on adult males; females and young are usually spared (although females may be subjected to sexual aggression). As long as military sorties had been described only for humans and chimpanzees, their origin could be linked with hunting (chimpanzees diversify their diet with meat food). Spider monkeys do not hunt, and their example proves that the development of military skills is not connected with feeding. It should be noted that spider monkeys are not our close relatives. These are American (broad-nosed) monkeys, highly adapted to an arboreal way of life. Moving through the branches is helped, for these small (up to 10 kg) animals, not only by their long and thin ("spider-like") limbs but also by the grip of the tail. These monkeys are, it seems, inseparably bound to the trees. An individual shot by a hunter remains hanging in the branches; death does not loosen the dead grip of its limbs. Yet, strange as it may be, for military sorties the monkeys descend to the ground. The researchers supposed that this aids a more concealed movement (although it also creates the danger of attack by ground predators). In this context one may recall that the causes which compelled our ancestors to switch to two-legged movement across the ground have not been definitively clarified. Earlier it was thought that such an event was connected with the displacement of forests by savannas; now there are grounds to assert that the first bipeds were still forest dwellers. Perhaps it was war that set us on our feet? The spear as a step toward nuclear deterrence The modern geopolitical picture has taken shape to a considerable degree as a consequence of the fact that humankind possesses a weapon that does not allow even a superpower to feel itself secure. The nuclear cudgel has kept from coming to blows not only the USA and the USSR but, for example, India and Pakistan. The striving to acquire a superweapon, or to prevent its spread, largely determines modern politics. When did such a process begin and where does it lead? Raymond Kelly, an anthropologist from the University of Michigan in Ann Arbor, believes that new relations between neighbouring groups of people arose about a million years ago, with the invention of the spear. Considering, for example, the behaviour of chimpanzees, we can see that the outcome of one conflict or another is determined above all by the numbers of the competing groups. A strong group may refuse to put up with a stranger or with weaker neighbours: the result of the clash is predetermined. With the appearance of the spear, and all the more of the bow, even a weak group was able to use the effect of surprise and inflict considerable damage on a superior opponent.

The oldest spears found by palaeoarchaeologists are about 400 thousand years old, but from indirect data one may suppose that this invention is no less than a million years old. So powerful an armament as the spear pushed neighbours toward peaceful coexistence. "A lean peace is better than a fat quarrel": it was easier for a strong tribe to go to a compromise with a weak one than to risk the lives of its members in fierce clashes. Of course, this peace was not devoid of aggression: a small enterprising group could, at its own risk, invade alien territory and gain some benefit from it. Under those conditions what mattered more was not strength and numbers but an alarm raised in time. Alas, at a certain stage society ripened to the point where a large group of people could plan a military campaign, gather warriors, and reconcile themselves to certain losses in the course of battles aimed at suppressing the opponent and seizing a substantial part of his resources. The possibility of real war appeared. Its outcome again came to depend on the numbers (and training) of the warring sides. The first traces of real wars known to us are about 14 thousand years old and were found in Sudan. Social organization was able to overcome the deterrent effect of the lethal weaponry of that time. This period ended only with the invention of the nuclear weapon: no social organization can compensate for the consequences of its use. The age of wars in which the strongest wins has ended (at least for nuclear powers; local wars still continue). And what then, have quiet and calm set in? No; as hundreds of thousands of years ago, the significance of sudden strikes has grown, in which the timely detection of danger is more important than military might. Such a mode of action is not a sinister invention of modern terrorists but merely reflects an ancient human tactic. D. Shabanov. A step toward a resurrected Neanderthal? // Computerra, Moscow, 2005. – No. 27‑28 (599‑600) D. Shabanov. An age of change // Computerra, Moscow, 2005. – No. 31 (603) D. Shabanov. Halfway to the superhuman // Computerra, Moscow, 2005. – No. 34 (606) D. Shabanov. Bipedalism – a bug? // Computerra, Moscow, 2004. – No. 35 (559). – pp. 13‑14 D. Shabanov.

The continuation of politics by other means, or?.. // Computerra, Moscow, 2006. – No. 19 (639) D. Shabanov. The spear as a step toward nuclear deterrence // Computerra, Moscow, 2005. – No. 37 (609). — pp. 17‑18