New fossils suggest human ancestors evolved in Europe, not Africa
Especialistas argumentam que as mandíbulas de um antigo macaco europeu revelam um ancestral humano chave.
26 April, 2019
- The jaw bones of an 8-million-year-old ape were discovered at Nikiti, Greece, in the '90s.
- Researchers speculate it could be a previously unknown species and one of humanity's earliest evolutionary ancestors.
- These fossils may change how we view the evolution of our species.
Homo sapiens have
been on earth for 200,000 years — give or take a few ten-thousand-year
stretches. Much of that time is shrouded in the fog of prehistory. What
we do know has been pieced together by deciphering the fossil record
through the principles of evolutionary theory. Yet new discoveries
contain the potential to refashion that knowledge and lead scientists to
new, previously unconsidered conclusions.
A set of
8-million-year-old teeth may have done just that. Researchers recently
inspected the upper and lower jaw of an ancient European ape. Their
conclusions suggest that humanity's forebearers may have arisen in
Europe before migrating to Africa, potentially upending a scientific
consensus that has stood since Darwin's day.
Rethinking humanity's origin story
The frontispiece of Thomas Huxley's Evidence as to Man's Place in Nature (1863) sketched by natural history artist Benjamin Waterhouse Hawkins. (Photo: Wikimedia Commons)As reported in
New Scientist,
the 8- to 9-million-year-old hominin jaw bones were found at Nikiti,
northern Greece, in the '90s. Scientists originally pegged the chompers
as belonging to a member of
Ouranopithecus, an genus of extinct Eurasian ape.
David
Begun, an anthropologist at the University of Toronto, and his team
recently reexamined the jaw bones. They argue that the original
identification was incorrect. Based on the fossil's hominin-like canines
and premolar roots, they identify that the ape belongs to a previously
unknown proto-hominin.
The researchers hypothesize that these proto-hominins were the evolutionary ancestors of another European great ape
Graecopithecus, which the same team tentatively
identified as an early hominin in 2017.
Graecopithecus
lived in south-east Europe 7.2 million years ago. If the premise is
correct, these hominins would have migrated to Africa 7 million years
ago, after undergoing much of their evolutionary development in Europe.
Begun
points out that south-east Europe was once occupied by the ancestors of
animals like the giraffe and rhino, too. "It's widely agreed that this
was the found fauna of most of what we see in Africa today," he told
New Scientists. "If the antelopes and giraffes could get into Africa 7 million years ago, why not the apes?"
He recently outlined this idea at a conference of the American Association of Physical Anthropologists.
It's worth noting that Begun has made similar hypotheses before. Writing for the
Journal of Human Evolution in
2002, Begun and Elmar Heizmann of the Natural history Museum of
Stuttgart discussed a great ape fossil found in Germany that they argued
could be the ancestor (broadly speaking) of all living great apes and
humans.
"Found in Germany 20 years
ago, this specimen is about 16.5 million years old, some 1.5 million
years older than similar species from East Africa,"
Begun said in a statement then. "It suggests that the great ape and human lineage first appeared in Eurasia and not Africa."
In the
Descent of Man,
Charles Darwin proposed that hominins descended out of Africa.
Considering the relatively few fossils available at the time, it is a
testament to Darwin's astuteness that his hypothesis remains the leading
theory.
Since Darwin's time, we have unearthed many more fossils
and discovered new evidence in genetics. As such, our African-origin
story has undergone many updates and revisions since 1871. Today, it has
splintered into two theories: the "out of Africa" theory and the
"multi-regional" theory.
The out of Africa theory suggests that the cradle of all humanity was Africa.
Homo sapiens
evolved exclusively and recently on that continent. At some point in
prehistory, our ancestors migrated from Africa to Eurasia and replaced
other subspecies of the genus
Homo, such as Neanderthals. This is the
dominant theory among scientists,
and current evidence seems to support it best — though, say that in
some circles and be prepared for a late-night debate that goes well past
last call.
The multi-regional theory suggests that humans evolved
in parallel across various regions. According to this model, the
hominins
Homo erectus left Africa to settle across Eurasia and
(maybe) Australia. These disparate populations eventually evolved into
modern humans thanks to a helping dollop of gene flow.
Of course,
there are the broad strokes of very nuanced models, and we're leaving a
lot of discussion out. There is, for example, a debate as to whether
African
Homo erectus fossils should be considered alongside Asian ones or should be labeled as a different subspecies,
Homo ergaster.
Proponents of the out-of-Africa model aren't sure whether non-African humans descended from a
single migration out of Africa or
at least two major waves of migration followed by a lot of interbreeding.
Did we head east or south of Eden?
Not all anthropologists agree with Begun and his team's conclusions. As noted by
New Scientist,
it is possible that the Nikiti ape is not related to hominins at all.
It may have evolved similar features independently, developing teeth to
eat similar foods or chew in a similar manner as early hominins.
Ultimately,
Nikiti ape alone doesn't offer enough evidence to upend the out of
Africa model, which is supported by a more robust fossil record and
DNA evidence.
But additional evidence may be uncovered to lend further credence to
Begun's hypothesis or lead us to yet unconsidered ideas about humanity's
evolution.
Related Articles Around the Web
Nenhum comentário:
Postar um comentário
Observação: somente um membro deste blog pode postar um comentário.