Human evolution

• Timeline of the Universe before the advent of planet Earth
• The history of the Earth before the appearance of hominids

Monkeys accumulate human traits

7 million hp: The beginning of the transition to straight walking due to the formation of the East African fault

Main article: East African Fault (rift valley)

About 7 million years ago, the first cases of straight-walking appear in Africa. The tectonic movements of the East African fault led to the rise of the ridges and this territory was fenced off from another part of Africa, where moist rainforests remained. Savannas and semisavannas formed in the fault zone due to a drier climate, so distant human ancestors were forced to go straight to survive. In addition, active volcanism in these territories provided the opportunity to find material for the manufacture of stone tools. Volcanic ash fertilized the soil and attracted herds of animals - the feed base of early human forms.

Sahelanthropes in Chad

Sahelanthrope - the exact age of the sahelanthrope at the moment cannot be established. The remains were discovered in Chad. The morphology of the found femur may cast doubt on its bipedalism (bipedalism). He may not have been a human ancestor, but a gorilla.

5.8 million hp: Upright walking is an element of adaptation to life on trees. Orrorins

• 6.1-5.8 million hp: Orrorin - the remains were found in Kenya and lay between two layers of volcanic ash, thanks to which they date relatively accurately: between 5.8 and 6.1 million years ago. Orrorin could not fully straighten the lower limbs in the hip joint.

Judging by the remains of animals and plants of the same era, orrorins lived in dry evergreen forests, and not in savannah, as many theories of human evolution predicted. Therefore, upright monkeys apparently first appeared in forests, and did not evolve from tetrapods that went out into open spaces. Upright walking may have been an element of adaptation to tree life. Modern orangutans use all four limbs to move only along thick twigs, while to thinner branches either cling from below or walk along them on the hind limbs, preparing the anterior to cling to other branches higher or balancing for stability. Such tactics allow them to approach fruits located far from the trunk, or jump from one tree to another. In contrast, the ancestors of modern chimpanzees and gorillas specialized in climbing vertical trunks and lianas, which is due to their crooked and clubfoot gait on the ground.

5.5 million hp: Ardipitek kadabba

The remains of Ardipitek Kadabba (5.5 million hp) were found in Ethiopia in a number of locations of the Middle Awash River valley, southeast of Hadar. Kadabb fangs are comparable in size and shape to fangs of small female chimpanzees and even larger than those of Orrorins. "Monkey" features were completely prevalent in the structure of the skull and arms, but "human" features appear and accumulate in the structure of the legs.

Ardipithecus kadabba. Reconstruction performed by Oleg Osipov

4.4 million hp: Ardipitec ramidus

Reconstruction of the skeleton Ardipitec ramidus

The remains of Ardipitec ramidus ("Ardi," 4.4 million hp) were discovered in Ethiopia. Fragments of almost all skeletal bones are known. The skull is no fundamentally different from the skull of Sahelanthropus, they, in fact, could be combined into one species, they are so similar. Like Sahelanthropus, in the structure of the skull, "human" features are only the occipital opening shifted forward and the small size of the fangs. The absolute size of the brain is extremely small. In the structure of the bones of the hands, "monkey" signs prevail. A number of signs indicate the possibility of quadrupedal support on the palm. The proportions of limbs relative to chimpanzees seem to be "human," but the arms relative to the legs are longer even than those of proconsuls and modern monkey-shaped ones, so that the proportions of arms and legs are more primitive than "human." Thus, Ardipitec ramidus collectively has more "monkey" features, only some signs of the hand, pelvis and leg associated with upright walking are "human," which are also, however, imperfect and combined with tetrapods and tree climbing. According to the shape of the pelvis and limbs, as well as the spaced big toe, it was established that Ardi was an optional bipedal. The cladistic approach, no doubt, would relate ramidus to monkeys, the importance of the upright walking complex in the eyes of researchers outweighs and allows us to talk about the hominidity of the Ardipiteks^[1]

Australopithecuses

4.2 mln LN - 3.9 million liters: Australopithecus anamus

Australopithecus anamus (lifetime 4.2 million liters - 3.9 million liters). Finds in two locations in Kenya - Kanapoi and Allia Bay, found about 100 fossils from more than 20 individuals.

Australopithecus anamensis. The reconstruction was carried out by Oleg Osipov.

"Monkey" skull structure. Given the very large length and massiveness of the radial bone, elements of quadrupedal locomotion in Anamanian Australopithecus are very likely.

4 million hp - 2.5 million hp: Australopithecus Afarski is the most likely ancestor of man

Phylogenetic connections between Australopithecus are unclear, and no species has definitely been identified as the direct ancestor of the branch leading to Homo. Australopithecus all shared common features:

• bipedal body position, but with elements indicating climbing;
• human traits such as tooth structure;
• other traits indicating similarities to the appearance of monkeys.

Australopithecus afarensis is the most likely ancestor of the human lineage of evolution. The remains were found in Kenya, Tanzania and Ethiopia in a variety of locations.

Australopithecus afarensis. Reconstruction performed by Roman Evseev

The morphological features of Hadar Australopithecus, due to the representativeness of the material, have been studied very well and can serve as a kind of reference for comparison when describing other species of Australopithecus.

The skull of the Afar Australopithecus is characterized by a low, sloping forehead; the brow is powerful.

The complex structure of the distal part of the radial bone indicates that the Afar Australopithecus, or their immediate ancestors, could walk on the phalanges of the fingers.

After studying the "Big Man" (the remains of an individual 1.6 meters tall, found in Ethiopia in 2005), the researchers are sure that the "Afars" could walk and even run, almost like modern humans. The large tibia is surprisingly long. This refutes the existing belief that long legs developed in later hominids, as an adaptation that helps to more effectively pursue the victim when hunting. Afar Australopithecus have not led a life in trees for a long time.

The features observed in the skeleton of A. afarensis, indicating other methods of movement, can either be a legacy inherited from ancestors, or indicate a wide range of types of movement used by these Australopithecus, although upright walking was apparently among them the predominant type.

The foot morphology of "A. afarensis" also attests to the variety of locomotor species used by this species.

In general, the arms of "A. afarensis" were somewhat elongated relative to the legs, the corresponding index having a value intermediate between the values known for great apes and modern humans; also, legs relative to height were somewhat shorter than that of modern humans. Such proportions appear to be a consequence of the incomplete transition to bipedal upright, which, as already mentioned, is reflected in many details of limb bone morphology. Apparently, the walking of Afar Australopithecus was slower, and the length of the day transition was much less than that of modern humans.

The body sizes of Hadar A. afarensis are extremely variable. The difference reflects, apparently, sexual dimorphism, which turns out to be equal to that of orangutans and gorillas and greater than that of chimpanzees and humans. The growth of small individuals barely exceeded a meter, while in large individuals it reached more than one and a half meters; the weight varied, respectively, from about 30 to 45 kg, possibly even up to 55 kg.

3.5 million hp: Traces of Australopithecus Afar in Laetoli in Tanzania

The 3.5 million-year-old human footprints found in Laetoli, Tanzania, may have been left behind by the species Australopithecus afarensis.

3.2 million LN: Lucy - Australopithecus Afar 1 meter tall

Among the numerous finds, the most famous is the partial skeleton of an adult woman AL 288-1. This find was named "Lucy." 40% of Lucy's skeleton was found on November 30, 1974 by D. Johanson and T. Gray in Ethiopia in deposits of the Kada Hadar pack with the most likely dating of 3.18-3.2 million liters.

Lucy's height - just over a metre

A significant part of the lower and upper limbs, spine, ribs, pelvis, lower jaw and parts of the skull have been preserved.

The structure of the pelvis of Australopithecus afarensis, which is sharply different from the high narrowed pelvis of great apes and, on the contrary, is not distinguished from the pelvis of modern humans, is remarkable. The pelvis is extremely wide and short. The proportions of the pelvis of "Lucy" are in some respects even "ultrahominid."

African hominins, Ma

2 million hp: Hominins in Russia

Main article: Paleolithic in Russia

Homo erectus

1.6 million hp: Homo erectus "Boy from Turkana" in Kenya is the first hominid with fully human anatomical and behavioral traits

In 1984, a complete skull and about 80 fragments of the hominid skeleton were discovered. He was dubbed the "Boy of Turkana."

It became the first known hominid to display fully human anatomical and behavioral traits.

At the time of his death, "The Boy from Turkana" was 8-10 years old. Its height was 154 cm, it developed faster than modern humans, but slower than chimpanzees. If he had not died, then, growing up, he would have gained about 10 cm more and would have been about 164 cm tall. This figure fits well into the general evolutionary line from the stunted Australopithecus to the tall long-legged Cro-Magnons.

Рост minerals forms of hominids. KNM-WT 15,000 - A boy from Turkana, Homo erectus, or Homo ergaster, whose 1.5 Ma remains were discovered in Kenya near Lake Turkana. The figure shows its refined growth in adulthood, taking into account the failed growth by 10 cm

Hominins in Spain

Main article: Paleolithic in Spain

Denisovans and Neanderthals

• Denisovites
• Neanderthal men

Homo Sapiens

200 thousand hp: is Botswana the birthplace of modern humanity?

Analysis of ancient DNA indicated that the first members of Homo sapiens appeared off the banks of the Zambezi River, where they lived for about 70 thousand years before their descendants began to colonize Africa. This conclusion was reached by scientists whose article in October 2019 was published by the scientific journal Nature. See Botswana for more details.

Notes