The evolution of Humans happened a long time ago on the African continent and this phenomenon of human evolution started from around 2.2 million years ago.
“Where have I come from, where did you pick me up?” the baby asked
its mother ” – AS Quoted in, “THE BEGINNING” – by RABINDRANATH TAGORE
This introductory line of this poem echoes the eternal question of the human psyche as to where we emerged from and has been one of the driving forces behind creation myths and other fascinating stories. However, the science tracing our journey from the primates to the humans of today is equally riveting.
Around 4-1 Ma (million years ago), under the African sun, a slightly modified group of apes known as Homo habilis (handyman) materialized from the more primitive relatives Australopithecus sp. It is this Homo habilis that comprise the earliest representative of the genus Homo, a group that we belong. Homo habilis inhabited the earth during the Gelasian age of the Pleistocene epoch.
Let me tell you about our cousins
Humans evolved in Africa. In keeping with this, the African continent provides the most abundant source of fossils defining different stages of human evolution. One of our earliest ancestors belonged to the group Australopithecus. The term Australopithecus is derived from the Latin word ‘australis’ meaning southern and the Greek word ‘pithekos’ meaning ape.
This term was coined by anatomist Raymond Dart who studied the first Australopithecus specimen obtained from a limestone quarry in Tuang in South Africa. Since then, at least seven different species of australopithecines, namely Australopihthecus afarensis, A. africanus, A. bahrelghazali, A. anamensis, A. boisei, A. robustus, and9 A. aethiopicus have been discovered from different parts of Africa. Studies using microwear of teeth enamel and remains of dental plaques showed that Australopithecines were primarily frugivores and herbivores.
And then there are uncles and aunts(2.2-1.6Mya)
As I mentioned before, Homo habilis represents the earliest hominins from which Homo sapiens, we modern humans evolved. Homo habilis walked the earth sometime between. Eastern Africa, the habitat of Homo habilis, underwent climatic changes due to Quaternary glaciation (beginning 2.85 Ma in the Calabrian age and ongoing currently) decreased the forest while increasing Savannah (grasslands). This, in turn, affected food availability, and Homo habilis had access to more meat and marrow than Australopithecines.
Stone tools attributed to Homo habilis were found in the Olduvai gorge by Mary and Louis Leaky in 1960. These consist of stone choppers, among other things, thus supporting the meat-eating habits of this hominid; however, the current opinion is that Homo habilis were mostly scavengers hunting small animals. Homo habilis fossils are restricted to East Africa, and present evidence suggests that this species of hominid went extinct around 1.4Ma, and the baton of evolution now rested with Homo erectus.
Homo erectus and Homo ergaster existed around 1.8 Mya in the Calabrian age. Scholars are still debating whether the obtained specimens should be grouped under one species, or these two hominins should be considered two separate species. Currently, both species are found to be evolved from Homo habilis. The salient point, however, is that Homo erectus fossils have been discovered outside Africa, while current Homo ergaster fossils are restricted to Africa only.
The best-known example of Homo ergaster is a 1.5-million-year-old almost complete fossil considered to be a male sub-adult, probably 7-12 years of age at the time of death. This specimen, discovered in 1984 in Kenya, is commonly referred to as ‘Turkana Boy’ or alternatively Nairokotome Boy named after the Lake Turkana and nearby Nairokotome river on the shores of which the skeleton was found.
Multiple Homo erectus fossils have been discovered in Dmanisi, in the Republic of Georgia, China, and Indonesia, all outside Africa. The earliest of the skeletal remains, colloquially known as ‘Java man,’ was found in 1891 along the banks of Sunngai Bengawan solo river by a Dutch military surgeon named Eugene Dubois. The initial excavation remains consisted of a skull, femur, and molar teeth, and based on this, Dubois named the species Pithecanthropus erectus meaning “upright ape-man.”
At the beginning of the 1920s, fossils began to be excavated in caves and a quarry in Zhoukoudian, about 42 km from Peking, currently known as Beijing. The fossils discovered in this region as commonly known as ‘Peking Man.’ In 1927, a single tooth from the excavation was used by Canadian anatomist Davidson Black to classify this fossilized species to the human lineage.
Subsequent excavations led to the finding of more bones, including 15 jawbones, 157 teeth, three upper arms, seven femurs, one shinbone, one collar bone, one wrist, and a collection of six complete or nearly complete skulls, 14 cranial fragments, six facial fragments.
Though Black named this species Sinanthropus pekinensis, the current classification considers this species to be Homo erectus. Detailed analysis of the remains suggests that Peking Man is more evolved than Java man, but the two are related, and the limbs of Peking Man seem to be like modern humans.
Interestingly the original fossils got lost during the second world war, and current specimens are mostly plaster casts. In 1987, UNESCO declared Zhoukoudian to be a world heritage site, and fresh excavations under Chinese patronage and leadership began in 2009. Since the debate about Homo erectus and H. ergaster being two different species is still ongoing and undecided we will consider them to be a single species Homo erectus with Homo ergaster being the African Homo erectus (since all the fossils were discovered in Tanzania, Ethiopia, Kenya, all in Africa).
Contrary to the primitive Homo habilis’s dependence on scavenging to obtain proteins, Homo erectus was active hunter-gatherers. This is reflected in the complexity and variety of the stone tools attributed to this hominin species. These hunters used stone tools of both lithic cores and flakes. Flake tools consist of sharp-edged fragments of stone obtained by breaking a desired stone or rock, and the core is the leftover nucleus after flaking.
Typically, hand axes were made of the lithic core, and flakes could were used as scrapers and burins. The two tools were found in many sites along with the fossils of other animals around Homo erectus excavation site. In addition to advanced tools, Homo erectus seems to have known the use of fire utilizing to cook food and protection against other large predators.
All these features made Homo erectus the most successful hominid to ever live ( the specimens found in China and Indonesia are about 70,000 years old) and the first hominin to migrate out of Africa dispersing throughout Eurasia during the Calabrian age of the early stage of Pleistocene era.
And finally our common ancestors
Multiple hominin species occupying the anatomical and temporal space between Homo erectus and anatomically modern Homo sapiens are collectively known as archaic humans. Prominent features distinguishing archaic humans from the more primitive Homo erectus are a larger brain case housing a bigger brain (1000-1400 cc), taller, less angular, and more parallel-sided cranial vaults, robust arching supraorbital tori (brow ridges), greater body mass and in some instances wider nasal apertures.
In comparison with modern humans, archaic humans had larger faces, again with more robust brow ridges, and lower thick-walled cranial vaults. Archaic humans had better control over fire and thus used fire more regularly, probably this controlled and regular usage of fire helped them to migrate to and thrive in the temperate climates of Eurasia. A few of the well-known species of archaic humans are described below:
Homo heidelbergensis: This species is named after the first fossil discovered in Mauer, a town close to Heidelberg in Germany. Since the discovery in Mauer in 1907, multiple h. heidelbergensis fossils have been found in Africa (Ndutu in Tanzania, Bodo in Ethiopia, and Kabwe in Zambia), Europe (Arago in France, Petralona in Greece) and possibly in Asia (Dali in China) as well.
The most recent find known as ‘Boxgrove Man’ was excavated from a quarry in Boxgrove close to surrey in England. Homo hiedelbergensis was an adept hunter as evidenced by the stone, bone, and wooden tools along with the bones of large, now extinct mammals discovered in excavation sites.
The discovery of red Ochre (probably used as body adornment) in Terra Amata, an open-air archaeological site in France and 28 skeletons in a pit in Atapuerca in Spain, points to the cultural aspect of this hominin. H. heidelbergensis might have been the earliest hominin to bury their dead ritually. The current theory is that European Neanderthals (H. neanderthalensis) are evolved from the European branch of H hiedelbergensis while the African branch gave rise to us Homo sapiens.
Homo antecessor: This is another extinct hominid species discovered yet only in Europe that too restricted to the Atapuerca mountains in Spain. This species existed between 800,000 to 1.2 Mya and was most likely nomadic trailing the food sources. Though they used tools, these were simple flakes used for cutting without the sophistication seen in tools of this period from other sites.
Multiple fossils were discovered in 1994-1996 (Gran Dolina) and 2007-08 (Sima del Elfante). This second excavation location harbored a knapping site presenting flakes with the clear elucidation of manufacturing techniques. Direct hammer percussion seems to be applied to detach the artifacts from medium-sized cores held in hand.
Homo rhodesiensis: ‘The Rhodesian man’ refers to an extinct archaic hominid living in Africa between 400,000 and 125,000 years ago. The type specimen for this group was discovered by Tom Zwiglaar in 1921 in a place named broken hill in northern Rhodesia and is commonly referred to as the ‘Broken Hill’ skull or the ‘Kabwe skull.’ Current speculation is that H rhodesiensis evolved into Homo sapiens idaltu (Herto man) from which we, Homo sapiens sapiens are directly descended.
Archaic humans in Asia have been discovered in both India and China. Excavation sites in Jinniushan, Dali, and Maba in China yielded practically complete crania which are 130,000 to 200,000 in age. Fossils from Jinniushan include postcrania as well. Though heavily distorted and thus difficult to estimate, two crania from a site Yunxian are also classified as archaic Homo sp due to the shape of the brow ridge. In India, the oldest hominid remains consisting of a partial calvaria are from a site in the Narmada valley and is dated to be 125,000-150,000 years old.
Image Credits:
Featured Image: Evolution of human
Skull development @Parker_West
Ph.D. Bio-science,
Cell Signalling Lipid
Bengaluru, India
