Extinct human species evolved rapidly to survive climate change by adapting its jaw and teeth to eat tougher foods, 2 million-year-old fossil reveals
- The emergence of Paranthropus robustus happened around 2 million years ago
- At the same time Homo erectus, ancestor of humans, also emerged Africa
- Primitive species, Australopithecus, went extinct and all due to climate change
- Believed the P. Robustus species then evolved tougher teeth and stronger chewing muscles to survive on the chewy food in the now arid region
A species of ancient human that lived two million years ago was forced to evolve and change its physical traits in order to survive climate change.
The emergence of Paranthropus robustus happened roughly at the same time as the more primitive hominin species Australopithecus died out.
It is believed this period of rapid change in South Africa occurred due to significant climate change forcing animals to adapt, or die.
During this period of time the first members of the Homo genus, of which modern humans are descended, also emerged.
Homo erectus and P. robustus took different approaches to the changing world, with the former developing a big brain to make tools in order to tackle the issue of hard, chewy food sources.
The latter, however, underwent physical changes and evolved larger teeth and powerful chewing muscles over 200,000 years — a rapid evolutionary intervention.
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The emergence of Paranthropus robustus (pictured, skull of DNH 155) happened roughly at the same time as the more primitive hominin species Australopithecus died out. It is believed a period of rapid change in South Africa occurred due to significant climate change forcing animals to adapt, or die
‘These two vastly different species, H. erectus with their relatively large brains and small teeth, and P. robustus with their relatively large teeth and small brains, represent divergent evolutionary experiments,’ said Angeline Leece of La Trobe University, the other first author of the study.
‘While we were the lineage that won out in the end, the fossil record suggests that P. robustus was much more common than H. erectus on the landscape two million years ago.’
Neanderthals and Homo erectus, both cousins of modern-day humans, went extinct due to sudden, and unexpectedly intense, bouts of climate change.
Scientists have long sought to understand the fate of our long-lost brethren, and previous studies have indicated climate change likely plays a major role.
Computer analysis, published last month, reveals the hominins failed to adapt to a rapidly changing climate.
Researchers investigated temperature, rainfall and other data over the last five million years to get a gauge of the climate for every 1,000-year window.
They also modelled the evolution of Homo species’ through time by plundering an extensive database of more than 2,750 fossils.
The analysis revealed three Homo species – H. erectus, H. heidelbergensis and H. neanderthalensis – lost most of their ‘climatic niche’ just before going extinct.
Climactic niche describes a locale where conditions are just right for the species to survive, not too hot, dry, cold or barren.
According to the researchers, Neanderthals were wiped out around 40,000 years ago and Homo erectus went extinct 70,000 years before that.
Researchers discovered a new fossil of the P. robustus species in the fossil-rich Drimolen cave system northwest of Johannesburg in the so-called Cradle of Humanity.
They compared this to others of the same species which had previously been found.
Existing theories claimed there was a large amount of variance in the size of the males and females of the species, a phenomenon known as sexual dimorphism seen in many living animals.
However, the new specimen, called DNH 155, which is clearly male and believed to be the best preserved example of his species, dispels this.
The researchers, from Washington University in St Louis and La Trobe University in Australia, now think it exemplifies the way the species physically changed.
One notable trait that changed over time is its dentition.
Dr Leece says: ‘We now know that tooth size changes over time in the species, which begs the question of why.
‘There are reasons to believe that environmental changes placed these populations under dietary stress, and that points to future research that will let us test this possibility.’
Existing fossils from the time this species existed prove mammals that relied on woods and bushland went extinct while other species associated with drier, more open environments appeared in the area for the first time.
P. robustus, which appeared at this time of flux, was built for the arid conditions.
Professor David Strait, professor of biological anthropology at Washington University, says as a result it was well-suited to eating tough foods that grew in this new climate.
‘P. robustus is remarkable in that it possesses a number of features in its cranium, jaws and teeth indicating that it was adapted to eat a diet consisting of either very hard or very tough foods,’ he said.
Existing theories claimed there was a large amount of variance in the size of the males and females ofParanthropus robustus , a phenomenon known as sexual dimorphism. However, then new discovery, which is clearly male and believed to be the best preserved example of his species, dispels this, researchers say. The specimen (pictured) is called DNH 155.
‘We think that these adaptations allowed it to survive on foods that were mechanically difficult to eat as the environment changed to be cooler and drier, leading to changes in local vegetation.’
The researchers found that the earliest members of this species had chewing muscles which were weaker than their descendants.
Over the course of 200,000 years, a dry climate likely led to natural selection favouring the evolution of a more efficient and powerful feeding apparatus in the species,’ says Professor Strait.
The findings are published in the journal Nature Ecology & Evolution.
Human ancestor Homo erectus may have lived two million years ago and emerged in South Africa – 200,000 years before previously thought
Man’s direct ancestor Homo erectus could be 205,00 years older than previously thought and may have emerged in South Africa, researchers have said.
Analysis of ancient skull fragments found near Johannesburg push the origin of the species back further than was believed.
It also moves the site of the species’ origin to South Africa, as it was previously thought to be further east.
The previous theory stated the primitive hominin emerged in East Africa 1.8 million years ago but fresh research moves this to between 2.04 and 1.95 million years ago.
The researchers, from US, South Africa and Australia, believe H. erectus lived alongside two other hominins at this time — Australopithecus and Paranthropus.
They said their discovery, detailed in the journal Science, may have implications for the origins of modern humans as H. erectus is a direct human ancestor.
It is best known for migrating out of Africa into the rest of the world.
The H. erectus skull bone named DNH 134 was unearthed in Drimolen – one of the archaeological sites in the Cradle of Humankind, 30 miles from Johannesburg.
They believe the skull DNH 134 was ‘likely aged between two and three’ and was dated to between 2.04 to 1.95 million years old.
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