Are Homo Sapiens generally lazy

Homo sapiens? - Pan sapiens! On February 14, 1747, the famous botanist Carl Linnaeus vented his anger in a letter to the Siberia researcher Johann Georg Gmelin: “I ask you and the whole world about a generic difference between humans and apes, ie how the principles of natural history demand it . I really don't know anyone and I wish that someone would just name one. If I had called man an ape or vice versa, I would have all the theologians after me; if I had done it properly, I would have really had to »(Gmelin 1861: 55). What happened? Twelve years earlier, Linnaeus had presented an extremely ambitious program in the first edition of his System of Nature. As he later wrote, he wanted to name and classify nothing less than "EVERYTHING that occurs on earth" (1751: 1). Everything - for him, this not only included all kinds of plants, minerals and animals, but of course also people. The species Homo sapiens (reasonable person), as he called it, was assigned first rank, but was placed among the four-legged animals ('Quadrupedia') and had to share the order Anthropomorpha (the human figures) with monkeys and sloths. From the tenth edition of the System of Nature (1758) he replaced the name “Quadrupedia” with “Mammalia” (mammals), and the anthropomorpha became the primates, from Latin: the first. He removed the sloths from close proximity to humans (and replaced them with bats), but at the point that had earned him the most criticism, he was not deterred: humans remained part of nature's system, and they stood close to the monkeys. From today's point of view, one can smile at the excitement of Linnaeus's contemporaries, after all he had only created a system of order that also only referred to well-defined physical characteristics. Linnaeus, like almost all natural scientists of his time, was convinced of this, as was the case with almost all natural scientists of his time. So in many ways his system was an uncertain first step. At the same time, however, it marked the beginning of an ideological revolution, the consequences of which are only slowly emerging in people's consciousness. From now on they were part of nature, one species among many. The age-old question of human nature could not only, no, it had to be investigated using scientific methods. Philosophers and theologians understood this challenge very well: From now on biology would itself be an anthropology, a doctrine of man. And today? What are the chances of the proposal to "call man a monkey or vice versa"? Molecular genetic studies have shown that humans share more than 98 percent of their DNA and almost all genes with chimpanzees (with mice, for example, it is around 80 percent). Animal species with such a small genetic make-up Fig. 1: In 1699 the first scientific study of a chimpanzee by the doctor Edward Tyson appeared. Homo sapiens? - Pan sapiens! 11 are usually assigned to a single genus. As Jared Diamond suggested a few years ago, humans would then be the third chimpanzee species, Pan sapiens (Diamond 1998; Nature 2005), alongside chimpanzees and bonobos. Linnaeus would have been happy about this late justification of his ideas by modern life sciences. Linnaeus did not interpret the similarity between humans and apes as a result of material relationship and evolution, but rather believed that each species was created separately. Some of his contemporaries were less hesitant, and soon people began to speculate about humans as modified apes and vice versa. However, the theory of evolution did not gain acceptance until a century later, when Charles Darwin was able to show how the properties of living beings change in the interplay of heredity and selection. The natural system became the basis for the family tree of all organisms. Common descent, wrote Darwin, is "the only known cause of resemblance in living beings" (1859: 456). The conclusion from similarity to relationship is not correct in all cases, but with the choice of suitable characteristics and methods it is very well suited to create reliable family trees. What evidence is there for the primate ancestry of humans? Primates are an order of mammals with around 230 species living today. Wet-nosed monkeys (Strepsirhini) and tarsier (Tarsiiformes) used to be grouped together as prosimiae. The so-called real monkeys are divided into the New World monkeys of America (Platyrrhini, wide-nosed monkeys) and the Old World monkeys of Africa and Asia (Catarrhini, narrow-nosed monkeys). The Old World monkeys include the tailed monkeys (Cercopithecoidea) and the great apes including humans (Hominoidea). “Primates” is the scientific name for a group of animals that is colloquially known as “monkeys” in German. In this sense, do the 12 Homo sapiens come from? - Pan sapiens! Humans of course from apes or great apes, but not from today's, but from fossil species. The origins of primates date back more than 65 million years (MJ) to the time of the dinosaurs. From fossil finds and molecular biological data we know that the common ancestors of the so-called real monkeys (in contrast to the half-apes) lived in Africa around 40 MJ. This is also where the New World monkeys come from, which reached South America either via the Atlantic Ocean or via Antarctica, which was not completely ice-covered at the time. About 28 MJ ago, the larger, tailless great apes separated from the tail monkeys (monkeys, baboons, etc.) in Africa. Remarkably complete fossils of early great apes have been preserved from species of the genus Proconsul in East Africa (20–17 MJ old). Although Proconsul is probably not the direct ancestor of today's great apes, it gives an impression of what it might have looked like (Stewart & Disotell 1998). Most primates are adapted to life in tropical forests. The flat face, with the eyes on the front of the head, enables three-dimensional vision - vital for species that can be found by shackling, climbing, and fig. 2: Family tree of primates living today? Primate descent of humans? 13 moving and jumping on trees and branches. Few primates such as jeladas, hussar monkeys, and humans live in open areas where they have to walk on the ground. And only humans are bad climbers, because their feet have lost their ability to grasp by adapting to persistent walking on two legs. Anatomical Evidence Even the naturalists of the 18th century knew that humans matched the great apes in their anatomical structures down to the smallest detail. And although some scientists tried their best to find an absolute difference - in the number and arrangement of bones, in the structure of the brain, or in other properties - each of these supposed findings proved to be deceptive. For a while it has been suggested that humans lack the intermaxillary bones in which the upper incisors are rooted in mammals. No less a person than Johann Wolfgang von Goethe could show that humans agree with other animals in this detail as well (Junker 2004 a: 42–3). The result of the search for a qualitative anatomical uniqueness of the people was negative overall. What was found were quantitative deviations - in the proportions of arms and legs, in the hair and Fig. 3: Artistic reconstruction by Proconsul (after Bonis 2001-02) 14 Homo sapiens? - Pan sapiens! Pigmentation of the skin or the relative size of the brain. Molecular biological evidence The question was no longer whether, but how humans are related to the other great apes. Since the great apes differ quite significantly in their external appearance, the way they move and in their behavior, the majority of biologists suspected until the 1990s that chimpanzees, gorillas and orangutans are more closely related to one another than to the People, and united them in the Pongid family. The trunk line that leads to the people would have split off first. It was one of the great successes of molecular biology that, by comparing proteins and DNA, it was able to clearly determine both the parentage relationships and the approximate times of the splitting. One of the oldest controversies in primate research was thus resolved. Fig. 4: The ideas about the relationships between the great apes have changed fundamentally as a result of investigations into genetic material (DNA). On the left the traditional scheme in which humans go through a long, independent evolution. On the right the new model, in which humans and chimpanzees are closely related (after Foley 2000). Primate ancestry of humans? 15 The now generally accepted result was that humans and chimpanzees are most closely related, then with gorillas and finally with orangutans (Pilbeam & Young 2004). The similarities between the other great apes that had misled biologists are therefore the result of their similar way of life and not the result of close genetic relationships. In humans, on the other hand, deviating characteristics have arisen because they have adapted to other ecological conditions - to life in tree and grass savannahs. The molecular clock The DNA comparison also has an invaluable advantage: You can not only determine the relative relationships, but also the approximate point in time at which the groups separated. The so-called molecular clock is based on the hypothesis that the genetic changes (mutations) in the examined DNA section occur at a constant rate over a certain period of time Great apes) Genus Hylobates (Gibbons, Siamangs) Family Hominidae (great apes, hominids) Subfamily Ponginae Genus Pongo (orangutans) Subfamily Gorillinae Genus Gorilla (Gorillas) Subfamily Homininae Tribus Panini Genus Pan (chimpanzees, bonobos) Tribus Homintribus Subininis Australopithecina (Australopithecinen) genera Sahelanthropus, Orrorin, Ardipithecus, Australopithecus, Paranthropus subtribus Hominina (humans) Genus Homo 16 Homo sapiens? - Pan sapiens! have taken place. In addition, if the absolute time of one of the branch points is known from independent data from paleontology or archeology, the other splits can be dated. Vincent M. Sarich and Allan C. Wilson, in their first study in 1967, estimated the separation between great apes and other Old World monkeys to be 30 million years, which would correspond to about 5 million years for the separation between African great apes (chimpanzees and gorillas) and humans . Until then, many paleoanthropologists had considered an independent evolution of the human lineage from 15 to more than 30 million years to be entirely plausible. More recent investigations have made corrections in detail, but the basic idea has proven itself. Molecular data have not only made the conventional classification that differentiated between humans and (other) great apes obsolete, but also revolutionized the concept of time. This in turn had important consequences for a whole range of ideas about human evolution. So, to name just one example, the longer shared history with the other great apes makes it much more likely that similarities can be observed in terms of mental abilities and not a largely isolated special path of humans. The method of reconstructing evolutionary family trees through DNA comparisons has now developed so far that a previously insurmountable limit is painfully noticeable: intact DNA is required, and that is only rarely the case with fossils. Paleontological Evidence From anatomical, physiological and other biological similarities one can see that humans belong to the primates and within the primates to the great apes. Molecular biology has confirmed this relationship and made it more precise: humans are African great apes, human primates? 17 most closely related to chimpanzees. To what extent do the fossil finds - the third important group of evidence - fit into the picture? The comparison of the data from anatomy, molecular biology and paleontology is highly informative, as they are obtained independently of one another. If they agree, this speaks for an increased certainty of the conclusions, if they contradict each other, one gains indications of possible errors. In this way, the thesis of the paleontologists could be refuted, for example, that the fossil monkey Ramapithecus from Pakistan, estimated to be up to 20 million years old, is one of the direct ancestors of humans. On the other hand, fossils are essential to review, calibrate and refine the family trees of molecular biologists. It was a sensation when a relatively well-preserved hominin skull was found a few years ago, which was dated 7 million years ago. Details of the teeth and jaws as well as a digital reconstruction of the skull of Sahelanthropus tchadensis make it probable that it is an upright hominin and not an ancestor of the gorillas (Brunet et al. 2002; Zollikofer et al. 2005). So it looks like the rough estimate of molecular biologists that the last common ancestor of humans and chimpanzees lived 5 to 8 million years ago should be revised upwards. The detailed reconstruction of family trees based on fossils is generally difficult. On the one hand, this is due to the incomplete nature of the fossil record, which Darwin lamented. Remnants of living beings are only preserved if they are covered by sediment and thus protected from further weathering. Then usually only the hardest parts of the body - teeth and bones - are found, while the skin, internal organs or muscles hardly leave any marks. And finally, paleontologists rely on the fossil-bearing strata being accessible, i.e. usually close to the surface. To the 18 Homo sapiens? - Pan sapiens! it is often unclear which exact position a fossil find occupies in the family tree. Paleontology is indispensable for research into human evolution, but for the reasons mentioned it often lags behind comparative anatomy and molecular biology in its results. In 1871, when Darwin's Descent of Man appeared, there was almost no fossil evidence of human evolution. The only exception were the remains of an unusual skeleton that had been found in a cave in the Neandertal near Düsseldorf in 1856. In 1891 the young doctor Eugen Dubois discovered skeletal remains on Java, which could be interpreted as an intermediate link between great apes and humans. Dubois ’Pithecanthropus erectus (‹ upright ape man ›) is now called Homo erectus. This also applies to the 'Beijing people' (Sinanthropus pekinensis), which was found in the area of ​​Zhoukoudian (40 km south of Beijing) in the late 1920s. As early as 1907, the paleontologist Otto Schoetensack had come across a well-preserved lower jaw southeast of Heidelberg, which was named Homo heidelbergensis. So by the mid-1920s, only a few fossils from later stages of human evolution had been discovered. And the localities were in Europe, Southeast Asia, and China, which seemed to confirm the widespread belief that humans originated in Central Asia. It was not until 1924 that Africa became the focus of paleoanthropological interest when Raymond Dart spoke about the discovery Fig. 5: The skull of Sahelanthropus tchadensis, which was presented to the public in 2002, is, according to its discoverers, the oldest known hominin find. Primate ancestry of humans? 19 of the skull of a hominin in South Africa reported. The first reactions to the find, which Dart called Australopithecus africanus (‹southern monkey from Africa›), were critical or even negative. Since the late 1950s, numerous Australopithecine fossils that have been assigned to different species have also been found in East Africa, especially at Lake Turkana (Kenya) and in the Olduvai Gorge (Tanzania), as well as in Ethiopia. The discovery of a comparatively complete skeleton of Australopithecus afarensis in the Ethiopian Afar Depression by Donald Johanson in 1974 was a sensation. The 3.2 million year old skeleton became famous under the name “Lucy”. Since then, numerous other finds have been made in Africa, although initially no hominin fossils older than 4.5 million years were among them. That only changed recently: with Ardipithecus ramidus (up to ~ 5.5 MJ), Orrorin tugenensis (~ 6 MJ) and Sahelanthropus tchadensis (6–7 MJ) this gap is also beginning to close.On the other hand, no fossil hominins older than 2 million years have so far been discovered outside of Africa. It is therefore now considered certain that the last common ancestor of humans and chimpanzees lived in Africa, as Darwin already suspected, and that the next phases of human evolution also took place here. From monkeys to people In the “beginning was carbon” - this motto should precede a tribal history of organisms, wrote Ernst Krause in Werden und Vergehen, a bestseller of the 19th century that introduced broad sections of the population to the new worldview of the theory of evolution (1886 : 93). Book and author are forgotten today, in their time saw 20 From monkeys to people