SF ASSIGNMENT- 1

Topic : which biological and cultural adaptations do you thinkwere important in the survival
of hominins in last 8-7mya.

Submitted by : Ananya Rajouria

Submitted to : Dr. Rashmi Pant
According to Darwinian Theory, the survival of species depends on their adaptive capabilities with
respect to their environmental pressures. From 8 to 7mya in late Miocene there were various
climatic oscillations which led to changes in East Africa’s environment. These changes created a
condition in which certain biological adaptations that were advantageous for survival became
established in hominin ancestors.
Bipedalism is considered as the most defining trait of the hominins and various hypothesis have
been put forward regarding it’s evolution ,for example- the Savannah hypothesis, postural feeding
hypothesis and the carrying hypothesis of Darwin. The evolution of efficient bipedal locomotion
in hominins came with certain Anatomical changes such as an arched foot, a lined big toe and the
creation of valgus angle in femur. Also an increased lumbar curvature of spine was evident that
protects the brain from shock.
The signs of bipedality among the oldest known hominin fossil, Sahelanthropas Tchadensis can be
seen through the anterior positioning of the foramen magnum in the basicranium which would
have provided support to the head in its limited terrestrial movement. The Ardi Skeleton gives
evidence of both arboreal and terrestrial adaptation of the species given the grasping position of
the divergent big toe in the foot and the curved phalanges of the limbs which suggest ape like
features.
The Australopithecines in this regard are considered to be terrestrial bipeds with an arboreal
capacity to climb up trees evident by their shorter lower limbs and bigger arms. They had funnel
shaped chest and curved fingers, however the major visible change was in foot morphology with
the lining of the big toe. The evidence to this comes from the footprints found in Laetoli, Tanzania
dated around 3.6mya.
A.afarensis species has some of the most key fossil discoveries including the 3.2 million year old
female skeleton, named Lucy discovered by Donald Johansson in Hadar, Ethiopia. Bipedalism in
its most efficient form first emerged in Homo erectus around 1.9mya with elongated thigh bones
and change in pelvis anatomy . Homo erectus had long striding gait and faster walk as compared
to early hominin ancestors.
Anatomical changes in pelvis were studied through the Turkana boy pelvis which was smaller than
modern human indicating at a narrower birth cavity. This alone would have led to neonate birth, a
biological adaptation to avoid mortality during childbirth. When an infant is born it’s average Brian
size is 385 cm3 or even more strained due to the mechanics of childbirth. This size gets tripled to
an average adult human cc of 1350cm3.This phenomenon of second altriciality is different from
primate development of brain. Thus, the premature birth of an infant alone becomes a factor for
prolonged childhood and increased dependency for care on mothers and at times grandmothers as
well in the social milieu.
Bipedalism also aided early hominins to forage for food in open grasslands and patchy woodlands.
The dietary habits of hominins can be traced through tooth wear patterns and enamel thickness.
Ardipithecus had large canines, less projecting than apes with thick enamel. The carbon isotope
studies suggest that they were plant eaters which also included Underground storage organs such
as tubers. Australopithecine and Paranthropines also ate a vegetarian diet with an exception of
A.Garhi.
The shift to a diet including meat was a culturally acquitted trait which was clearly visible in Homo
Habilis and then expands under homo erectus who are believed to be associated with early uses of
fire. Their jaws were small and round shaped with the disappearance of sharp canines. The
introduction of meat in the diet of early hominins was essential as it provided them with extra
nutrition ,required by an evolving brain.
Human brain differs from an ape as it includes a predominant parietal and temporal lobe with
increased convolutions in the frontal lobe as compared to the primates. Fossil evidence indicating
increase in brain size can be easily studied by the impressions of the convulsions on the crania
which can be useful in reconstructing the brain size of early hominins. The evidence regarding the
increase in brain size comes around 3 Mya with the genus Australopithecines . Among the gracile
Australopithecines, A.afarensis had a cc of 400cm3 which was roughly similar to an ape whereas
A.africanus which lived 3.3 -2.6 mya had a cc of 428-550cm3. A.africanus had a squared off skull
with a swooping shape at the bottom.
The Paranthropus genus had a small brain with a cc of 420 to 520cm3 whereas the shape was in a
teardrop pattern which was evident in P.Robustus skull. One reason cited for paranthropus having
smaller brains is the presence of a more robust jaw which required a sagittal crest to hold the
muscles of the jaw . Paleontologists suggest that it would have created a pressure on the cranium
and hence there was no space left for the brain to expand. Marked expansion in brain size is seen
in genus Homo specifically with Homo habilis/ rudolfenisis .The cranial capacity ranges from 610
to 750cm3 which is a significant increase as compared to the Australopithecine.
This expansion in brain size also led to changes in skull of H.Habilis and H.rudolfenisis which is
evident from fossil remains KNM-ER 1813 and KNM- ER 1470 respectively. The skull has
become more rounded with slight forehead, smaller brow ridges as compared to early ancestors.
The cranial capacity of homo erectus reached 1050cm3 with the skull becoming long and broad
with sharp angles at the rear and thick bones forming a midline keel at the top of the skull. The
complexity of the brain enhances with the enlargement of the parietal and frontal lobes in Homo
heidelbergensis brain which has a cranial capacity of 1250cm3. European populations of Homo
heidelbergensis evolved into Homo neanderthalensis which are assumed to have a cc of 1500cm3
,while a separate population of Homo heidelbergensis in Africa evolved into Homo sapiens which
have an average cc of 1350cm3 with a fully evolved globular structure of skull and reduction in
neck muscles. The skull has a short base and a high braincase with no post orbital constrictions.
The forehead becomes tall with squared eye sockets.
Anthropologist Robin Dunbar attributes the expansion of brain size to an increasing group size ,
according to him Homo Habilis shows a marked increase in cranial capacity as it lived in a band
size of approximately 81 which was essential in an environment dominated by predators . Homo
Habilis is also considered to be the first tool maker, it’s evidence coincides with the tool artefacts
of the Oldowan industry around 2.6mya and also a change in hand morphology which shows
humanlike precision for grip.
The tools of the lower Omo Valley were made up of lava cobbles, found in core and flakes form .
Nicolas Toth suggests that the real tools were the flakes formed by the direct percussion technique.
Although there is no direct evidence regarding the application of these tools, 9 out of 54 flakes
found at Koobi Fora, dated 1.5mya gave evidence of use wear including butchering , use in soft
vegetation and use on wood. The oldowan artifacts include hammer stone, polyhedron, unifacial
and bifacial chopper , scrapers.
As Homo eragaster/erectus moved out of africa, they were accompanied by major technological
changes in tool making where a shift from rudimentary to more precise tool making was
characterized by the presence of a tearshaped handaxe. The oldest specimen of it has been found
in Ethiopia dated around 1.4mya. These were part of the Acheulean Assemblage or mode 2
technology . Glyn Issac considers Acheulean as a further development of oldowan technique which
was marked by bigger bifacial flakes made out of ovoid cobbles. The Acheulean tools marked a
technological continuity of about 1.3 million years and came to an end around 200,000years ago.
The finds are scattered in large numbers in Europe , africa , western and southern asia however no
tool has been found in East Asia . The earliest Acheulean site outside Africa is Ubeidiya , dated
around 1mya.
Later, a more complex mode 3 technology of tool making known as Mousterian emerged around
250,000years ago associated with the Neanderthals and the early Homo sapiens. These tools were
made through Levallois technique which required abstract thought processing to shape the core
and then produce flakes. These include points , scrapers and some composite tools especially for
hunting and other related activities.
Some of the most extraordinary Mousterian finds are in Combe Grenal Cave of France. These
technological changes were also accompanied by some cultural adaptations related to religious
beliefs such as burying of the dead. Homo Neanderthals are considered to be associated with early
burials. At Qazfeh in Israel, some 115,000 years ago, there is evidence of deliberate burial. Some
bodies were laid down in pits with ochre and burial goods suggesting a belief in afterlife.
The increase in cognitive abilities of hominins is also related to the evolution of language and
symbols. Emergence of which can be traced by the positioning of larynx in the neck. Whereas in
brain Broca’s and Wernicke’s area are responsible for the production and perception of sound. All
these anatomical characteristics responsible for speech and language are considered to have been
evolved in archaic homo and Neanderthals. Language development is closely tied to the
development of imagery and art in the Palaeolithic period which requires similar cognitive base.
Prehistoric art carries different meanings which at times can be religious, abstract or related to
natural life. Most exemplary works of these arts are found in Europe particularly the cave of
Lascaux and Chauvet cave, dated 17,000 and 32,400 years ago respectively. The chauvet cave
have predominance of painted carnivores on the walls which include some unrepresented animals
such as hyenas and leopard. Beyond Europe, the earliest known figurative art comes from Apollo
11 cave in South Africa where some paintings are said have a shamanistic origin. Beruile argues
prehistoric art such as Australian – Aboriginal art to be related to hunting magic whereas Claude
considers thay the animals represented had no relation to hunting rituals and were only good to
think.
Some engravings had anthromorphic forms, for example – the lion headed statue found in Southern
Germany cave dated around 32,000years ago and others where at times superimposed or
interspersed with geometric patterns. The depiction of Venus figurines with exaggerated sexual
characteristics were also found in Willendorf, Austria and Dolní Vestonice, Czech Republic. Why
these early homo's started engaging in these cultural activities is still debated however most of the
naturalistic representations of art came to an end around 25,000 years ago. The culture itself leaves
no fossilised records and can be inferred only through interpretations which may change over time.
The emergence of Homo sapiens is debated between out of Africa and multiregional model.
Around 98 percent DNA of Anatomically modern humans coincides with Homo sapiens who
came out of Africa during the second wave of migration and then populated both the new and old
world. They survived through hunting , scavenging and around 90,000 years ago through fishing.
Within the past 12,000 years Homo sapiens made a transition and started to control resources
needed for subsistence through domestication of plants and animals.
Thus, it is evident that evolution deterministic or random have a sole purpose of survival and all
these adaptive changes can be at times linked to or reinforced by each other. The evolution of
hominins to Homo sapiens (sapiens) was not a liner process ,several species coexisted and
interbred with each other to produce new species for which some fossils may not be available.
Bibliography

Principles of Human Evolution by Robert Foley and Roger

Lewin
People of the earth by Brian Fagan and Nadia Durrani
https://www.britannica.com/list/human-ancestors
https://www.nature.com/scitable/knowledge/library/overviewhttps://www.nature.com/scit
able/knowledge/library/overview-of-hominin-evolution-89010983of-hominin-evolution-
89010983