Humanity may not bear the brunt of the blame for the extinction of our Neanderthal cousins, according to a new study, which suggests they could have been killed off by maintaining small populations and inbreeding without having ever come into contact with Homo sapiens.
Paleoanthropologists agree Neanderthals died out some 40,000 years ago – disappearing after 350,000 years on the planet, at roughly the same time that anatomically modern humans began to migrate out of Africa and into Europe and western Asia.
However, questions remain over how involved Homo sapiens were in the Neanderthal decline – with one theory suggesting modern humans may have been better at collecting resources than their hominid relations due to their capacity for high-level thought and social processing.
Now a study from the Eindhoven University of Technology, the Netherlands, has suggested that even without competition from humans, Neanderthals could have died out through the small scale of their populations, inbreeding, and random demographic fluctuations.
Lead author Krist Vaesen from Eindhoven University, along with her colleagues, asks: “Did Neanderthals disappear because of us?
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Bubbles want to optimise space and minimise their surface area for a given volume of air. This unique phenomenon makes them a reliable, useful tool in many areas of research. In particular, materials science and ‘packing’ – how things fit together. Bubble walls drain under gravity, thin at the top, thick at the bottom and interferes with travelling lightwaves to create bands of colour. Black spots show the wall is too thin for interference colours, indicating the bubble is about to burst! – Kym Cox
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Mary Anne Chilton/RPS
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David Spears/RPS
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Dave Watson/RPS
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Richard Germain/RPS
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Viktor Sykora/RPS
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Final Major Project for an MA Photography Falmouth University. Project: Mapping 1, Post Exertional Malaise. Mapping 1, focuses on discovering the research behind Myalgic Encephalomyelitis. Through exploration of perspective, complexities, and scientific multidisciplinary collaborations, I create imagery that explains, reveals and connects us consciously to the ambiguous and unknown. – Yasmin Crawford
Yasmin Crawford/RPS
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Marge Bradshaw/RPS
1/9 Soap bubble structures showing light interference colours and patterning
Bubbles want to optimise space and minimise their surface area for a given volume of air. This unique phenomenon makes them a reliable, useful tool in many areas of research. In particular, materials science and ‘packing’ – how things fit together. Bubble walls drain under gravity, thin at the top, thick at the bottom and interferes with travelling lightwaves to create bands of colour. Black spots show the wall is too thin for interference colours, indicating the bubble is about to burst! – Kym Cox
Kym Cox/RPS
2/9 Upside down Jelly fish, Cassiopea xamachana
Instead of swimming, this species spends its time pulsing up and down in the water. Their diet is sea plankton and their coloration comes from the uptake of algae in the water. Some jellyfish species have been documented eating plastics in the ocean. One theory suggests that algae grows on the plastic. As it breaks down, the algae creates the odor of dimethyl sulfide that attracts hungry animals. – Mary Anne Chilton
Mary Anne Chilton/RPS
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This small beetle is a pest in stored grain and flour products. Scanning electron micrograph, coloured in Photoshop. – David Spears
David Spears/RPS
4/9 NGC7000 North American Nebula
The North America Nebula, NGC7000, is an emission nebula in the constellation Cygnus, close to Deneb. The remarkable shape of the nebula resembles that of the continent of North America, complete with a prominent Gulf of Mexico. The Cygnus Wall, a term for the “Mexico and Central America part” of the North America Nebula, exhibits the most concentrated star formations in the nebula. – Dave Watson
Dave Watson/RPS
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A safety pin is connected to a high tension AC generator. The pin ionizes the air around it. When the electrons fall back on an atom, the excess energy is emitted as a photon, which generate the corona glow around the pin. The fuzziness of the pin is because the camera did not actually capture light reflected on the pin but rather the light emitted by the ionized light around it. – Richard Germain
Richard Germain/RPS
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Yevhen Samuchenko/RPS
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Stag beetle. Light microscopy. Magnification 5x. – Viktor Sykora
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9/9 Lovell Telescope Series 1c
I have always been fascinated with the Lovell Telescope at Jodrell Bank since I went on a school trip as a child. Here, I wanted to take a series of closer, more detailed and more honest shots than we often see. Exploring the multitude of shapes and exposing the wear of the telescope, each photo in the series stands alone or can be viewed collectively, either way, they present a powerful portrayal of machine that helps humankind in their endeavours to understand space and time. – Marge Bradshaw
Marge Bradshaw/RPS
“No, this study suggests. The species’ demise might have been due merely to a stroke of bad, demographic luck.
“Our results indicate that the disappearance of Neanderthals might have resided in the smallness of their populations alone – even if they had been identical to modern humans in their cognitive, social and cultural traits, and even in the absence of [competition for the same resources], Neanderthals faced a considerable risk of extinction.”
The study was conducted using data from hunter-gatherer populations that still exist, and creating population models to represent Neanderthal groups of different sizes.
Researchers then simulated the effects of inbreeding, Allee effects – a phenomenon where population size effects the fitness of members of the group – and random yearly changes in the numbers of births and deaths, as well as gender ratios.
From there they tested to see if these factors alone could have caused extinction over a period of 10,000 years – finding that while inbreeding by itself was unlikely to have led to the decline of Neanderthals, it could have had an impact when combined with a sudden decline in birth rates.
Reproduction-related Allee effects, which see females giving birth within a year to 25 per cent or less, are commonly seen in modern-day hunter-gatherer groups and could have caused extinctions in Neanderthal groups as large as 1,000 – according to the study.
Researchers hope that the study may now prove as a baseline to test competing theories on the exact cause of extinction for humanity’s distant cousins.
The study concludes: “Regardless of whether external factors [climate or epidemics] or factors related to resource competition played a role in the actual demise of Neanderthals, our study suggests that any plausible explanation of the demise also needs to incorporate demographic factors as key variables.”
