Let's write about homo sapiens!
HUMAN EVOLUTION
Christopher Brian Stringer FRS is a British physical anthropologist noted for his work on human evolution
But some commentators are now suggesting that the extinct Neanderthals with their heavy brows and big noses should be classified in our species as well.
Named by Linnaeus: Our species name (which means 'wise humans' - though we might question the wisdom of that name today) was given to us by that great Swedish classifier Carl Linnaeus in 1758. In those pre-evolutionary times, species were usually considered to be fixed identities, created by God.
Grouping living things in species allows biologists to study aspects of life ranging from our own evolutionary history to the conservation of rain forests in the Amazon.
Today we still recognize each species by its own special features.
How do Homo sapiens and Neanderthals differ?
The physical traits of Homo sapiens include a high and rounded ('globular') braincase, and a relatively narrow pelvis.
Measurement of our braincase and pelvic shape can reliably separate a modern human from a Neanderthal - their fossils exhibit a longer, lower skull and a wider pelvis.
Even the three tiny bones of our middle ear, vital in hearing, can be readily distinguished from those of Neanderthals with careful measurement. In fact the shape differences in the ear bones are more marked, on average, than those that distinguish our closest living relatives - chimpanzees and gorillas - from each other.
Named by Carl Linnaeus: Our species name (which means 'wise humans' - though we might question the wisdom of that name today) was given to us by that great Swedish classifier Carl Linnaeus in 1758. In those pre-evolutionary times, species were usually considered to be fixed identities, created by God.
Grouping living things in species allows biologists to study aspects of life ranging from our own evolutionary history to the conservation of rain forests in the Amazon.
Today we still recognise each species by its own special features.
How do Homo sapiens and Neanderthals differ?
The physical traits of Homo sapiens include a high and rounded ('globular') braincase, and a relatively narrow pelvis.
Measurement of our braincase and pelvic shape can reliably separate a modern human from a Neanderthal - their fossils exhibit a longer, lower skull and a wider pelvis.
Even the three tiny bones of our middle ear, vital in hearing, can be readily distinguished from those of Neanderthals with careful measurement. In fact the shape differences in the ear bones are more marked, on average, than those that distinguish our closest living relatives - chimpanzees and gorillas - from each other.
Stringer writes, "I still believe they are distinct species".
In the face of this seemingly decisive evidence, why do I cling to my belief that Neanderthals and Homo sapiens are distinct species?
Well, in my view the problem is not with ancient couplings between our ancestors and Neanderthals, but with the limitations of the biological species concept.
We now know from the same kind of genomic research that many other species of mammal interbreed with each other - for example different kinds of baboons (genus Papio), wolves and wild dogs (Canis), bears (Ursus) and large cats (Panthera). In addition, one recent estimate suggests that at least 16% of all bird species interbreed with each other in the wild.
Thus the problem is not with Neanderthals and modern humans and all the other species that interbreed with each other, but with the biological species concept itself. It is only one of dozens of suggested species concepts, and one that is less useful in the genomic age, with its profuse demonstrations of inter-species mixing.
Are Neanderthals the same species as us? Essay published in the Natural History Museum on line magazine, by Chris Stringer.
Museum human evolution expert Professor Chris Stringer, who has been studying Neanderthals and early modern humans for about 50 years, tackles the big question of whether we belong to the same species.
Human evolution
Everyone on the planet today, whatever they look like and wherever they live, is classified by biologists in the species Homo sapiens.
But some commentators are now suggesting that the extinct Neanderthals with their heavy brows and big noses should be classified in our species as well.
So what defines our species, and who qualifies to join the club?
An expanding family tree: When I drew up a family tree covering the last one million years of human evolution in 2003, it contained only four species: Homo sapiens (us, modern humans), H. neanderthalensis (the Neanderthals), H. heidelbergensis (a supposedly ancestral species), and H. erectus (an even more ancient and primitive species). I have just published a new diagram covering the same period of time and it shows more than double the number of species, including at least four that were around in the last 100,000 years.
Scientists currently recognize as many as nine human species from the past one million years, including the recently discovered Homo luzonensis, which was announced in April 2019.Named by Linnaeus: Our species name (which means 'wise humans' - though we might question the wisdom of that name today) was given to us by that great Swedish classifier Carl Linnaeus in 1758. In those pre-evolutionary times, species were usually considered to be fixed identities, created by God.
Grouping living things in species allows biologists to study aspects of life ranging from our own evolutionary history to the conservation of rain forests in the Amazon.
Today we still recognize each species by its own special features.
How do Homo sapiens and Neanderthals differ?
The physical traits of Homo sapiens include a high and rounded ('globular') braincase, and a relatively narrow pelvis.
Measurement of our braincase and pelvic shape can reliably separate a modern human from a Neanderthal - their fossils exhibit a longer, lower skull and a wider pelvis.
Even the three tiny bones of our middle ear, vital in hearing, can be readily distinguished from those of Neanderthals with careful measurement. In fact the shape differences in the ear bones are more marked, on average, than those that distinguish our closest living relatives - chimpanzees and gorillas - from each other.
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| Carl Linnaeus (1707-1778) Swedish zoologist |
Named by Carl Linnaeus: Our species name (which means 'wise humans' - though we might question the wisdom of that name today) was given to us by that great Swedish classifier Carl Linnaeus in 1758. In those pre-evolutionary times, species were usually considered to be fixed identities, created by God.
Grouping living things in species allows biologists to study aspects of life ranging from our own evolutionary history to the conservation of rain forests in the Amazon.
Today we still recognise each species by its own special features.
How do Homo sapiens and Neanderthals differ?
The physical traits of Homo sapiens include a high and rounded ('globular') braincase, and a relatively narrow pelvis.
Measurement of our braincase and pelvic shape can reliably separate a modern human from a Neanderthal - their fossils exhibit a longer, lower skull and a wider pelvis.
Even the three tiny bones of our middle ear, vital in hearing, can be readily distinguished from those of Neanderthals with careful measurement. In fact the shape differences in the ear bones are more marked, on average, than those that distinguish our closest living relatives - chimpanzees and gorillas - from each other.
Stringer writes, "I still believe they are distinct species".
In the face of this seemingly decisive evidence, why do I cling to my belief that Neanderthals and Homo sapiens are distinct species?
Well, in my view the problem is not with ancient couplings between our ancestors and Neanderthals, but with the limitations of the biological species concept.
We now know from the same kind of genomic research that many other species of mammal interbreed with each other - for example different kinds of baboons (genus Papio), wolves and wild dogs (Canis), bears (Ursus) and large cats (Panthera). In addition, one recent estimate suggests that at least 16% of all bird species interbreed with each other in the wild.
Thus the problem is not with Neanderthals and modern humans and all the other species that interbreed with each other, but with the biological species concept itself. It is only one of dozens of suggested species concepts, and one that is less useful in the genomic age, with its profuse demonstrations of inter-species mixing.
In fact, the reality is that in most cases in mammals and birds, species diverge from each other gradually. It may take millions of years for full reproductive isolation to develop, something that clearly had not yet occurred for H. neanderthalensis and H. sapiens.
In my view, if Neanderthals and Homo sapiens remained separate long enough to evolve such distinctive skull shapes, pelvises, and ear bones, they can be regarded as different species, interbreeding or not.
Humans are great classifiers, and we do like to keep things orderly. But we should not be surprised when the natural world (past and present) does not match up to our neat and simple schemes.
Behaviour is irrelevant here
But what about the archaeological evidence that is also commonly cited in favour of uniting the Neanderthals with us as Homo sapiens - that they had 'cultural' behaviours such as burying their dead and painting designs on the walls of caves?
Well, interesting as that is, it should be excluded from the biological classification of species, since behaviors are potentially more plastic, evolve more quickly, and spread more easily within and between species than traits based on anatomy and DNA.
In my view, if Neanderthals and Homo sapiens remained separate long enough to evolve such distinctive skull shapes, pelvises, and ear bones, they can be regarded as different species, interbreeding or not.
Humans are great classifiers, and we do like to keep things orderly. But we should not be surprised when the natural world (past and present) does not match up to our neat and simple schemes.
Behaviour is irrelevant here
But what about the archaeological evidence that is also commonly cited in favour of uniting the Neanderthals with us as Homo sapiens - that they had 'cultural' behaviours such as burying their dead and painting designs on the walls of caves?
Well, interesting as that is, it should be excluded from the biological classification of species, since behaviors are potentially more plastic, evolve more quickly, and spread more easily within and between species than traits based on anatomy and DNA.
Labels: Carl Linnaeus, Christopher Stringer, Natural History Museum
posted by Juliana L'Heureux at 8:19 AM
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