Models that will take pride of place in the Britain: One Million Years of the Human Story exhibition made their entrance last week.
Two eerily lifelike models of a Neanderthal and a Homo sapiens were delivered to the Museum on Friday, before being whisked off into hiding until early next year.
The specially commissioned models were created by the Kennis brothers, twin artists who specialise in scientifically accurate sculptures of ancient humans and animals.
Ancient visitors: the Neanderthal, left, is modelled on a Neanderthal who was in his 20s. The artists were surprised by scientific evidence of his anatomy, particularly his flat bottom. The Homo sapiens is based on a man in his 50s.
The naked models, both with tattoo-like markings, are wizened and look disturbingly similar to modern men. The Neanderthal is lighter-skinned than the Homo Sapiens, based on evidence from recent and ancient DNA.
The Neanderthal figure is modelled on a skeleton found in a cave in Belgium and is short and stocky, whereas the modern human, whose ancestors came from Africa, is much taller.
Drawing on scientific data, the Kennis brothers rebuilt the skeletons of these ancient humans in their studio in Arnhem in the Netherlands built up clay muscle and tendon and took a cast of each body. These were then filled with silicon to create the models.
They coloured and specked the silicon from the inside out to recreate accurate skin tone. Both Neanderthals and modern humans probably used pigment to mark their skin.
Museum palaeontologist Prof Chris Stringer, Director of the Ancient Human Occupation of Britain project (AHOB) that inspired the exhibition, provided replica bones and advised the artists on skin pigmentation, markings and hair style.
The AHOB project is a 13-year multidisciplinary collaboration between the Museum and Royal Holloway, Oxford and Cambridge Universities, the British Museum and Queen Mary University of London.
The exhibition itself has taken three years to create.
Neanderthals are our closest extinct relatives, and although our species, Homo sapiens, did not evolve from them directly, many of us have a small percentage of Neanderthal DNA as a result of ancient interbreeding.
Neanderthals were skilled toolmakers and hunters, great survivors who colonised Britain many times between 400,000 and 50,000 years ago, at times coping with ever-changing environments, and at other times disappearing.
Modern humans first arrived in Britain from Africa around 40,000 years ago. Homo sapiens were the first human species to sculpt objects not just for survival but to interpret the world around them, through artistic expression.
The models will take pride of place in the exhibition, Britain: One Million Years of the Human Story, which opens 13 February 2014.