全人类单一起源于非洲的新证据

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7月19日的英国《自然》杂志发表了支持了人类单一起源理论的研究结果。剑桥大学的这项研究将全球人类遗传变异与头骨尺寸结合了起来，彻底击垮了人类多起源论。该研究由（英国）生物技术和生物科学研究委员会(BBSRC)资助完成。

关于现代人的起源存在着针锋相对的多种理论：或认为人类单一起源与非洲并迁移至全世界，或认为不同地域的直立人独立地进化成人类。

剑桥的研究人员研究了全球人类种群的遗传变异和学术机构收藏的全球6,000多个头骨。他们的研究击倒了多起源论的最后支柱之一。新发现显示遗传多样性的丧失：一个种群距离非洲越远，身体素质上的多样性越少。

课题组长剑桥动物系的Andrea Manica博士解释说：现代人的起源一直是争论的焦点。我们的遗传学研究显示现代人类迁移出非洲越远，种群内遗传多样性丧失得越多。

“可是，有人曾用头骨数据来主张人类起源于全球多个地点。我们将我们的遗传数据和大量头骨样本的新测量数据结合起来，确切显示了现代人类起源于撒哈拉以南非洲的一个单一区域。”

研究小组发现随着各种群远离非洲，它们的遗传多样性降低了。这是人类迁移过程中随时间推移种群数量减少的一些瓶颈或事件的结果。他们于是研究异常多数量的人类头骨。通过对所有头骨的一系列检测，研究小组发现：不但非洲东南部样品检测结果的变化最大，而且这种变化的下降速率和逐渐离开非洲的遗传数据相一致。

为了确保他们关于单一起源的证据的可靠性，研究人员尝试了用他们的数据去查找非欧洲起源的现代人类。作为研究者之一的Francois Balloux解释说：“为了检测现代人类起源的不同理论，我们试着寻找另外一种不是非洲起源的人类。我们发现找不到。我们的发现现代人类起源于撒哈拉以南非洲的一个单一的区域”

来源：（英国）生物技术和生物科学研究委员会

New research proves single origin of humans in Africa

New research published in the journal Nature (19 July) has proved the single origin of humans theory by combining studies of global genetic variations in humans with skull measurements across the world. The research, at the University of Cambridge and funded by the Biotechnology and Biological Sciences Research Council (BBSRC), represents a final blow for supporters of a multiple origins of humans theory.

Competing theories on the origins of anatomically modern humans claim that either humans originated from a single point in Africa and migrated across the world, or different populations independently evolved from homo erectus to home sapiens in different areas.

The Cambridge researchers studied genetic diversity of human populations around the world and measurements of over 6,000 skulls from across the globe in academic collections. Their research knocks down one of the last arguments in favour of multiple origins. The new findings show that a loss in genetic diversity the further a population is from Africa is mirrored by a loss in variation in physical attributes.

Lead researcher, Dr Andrea Manica from the University's Department of Zoology, explained: "The origin of anatomically modern humans has been the focus of much heated debate. Our genetic research shows the further modern humans have migrated from Africa the more genetic diversity has been lost within a population.

"However, some have used skull data to argue that modern humans originated in multiple spots around the world. We have combined our genetic data with new measurements of a large sample of skulls to show definitively that modern humans originated from a single area in Sub-saharan Africa."

The research team found that genetic diversity decreased in populations the further away from Africa they were - a result of 'bottlenecks' or events that temporarily reduced populations during human migration. They then studied an exceptionally large sample of human skulls. Taking a set of measurements across all the skulls the team showed that not only was variation highest amongst the sample from south eastern Africa but that it did decrease at the same rate as the genetic data the further the skull was away from Africa.

To ensure the validity of their single origin evidence the researchers attempted to use their data to find non-African origins for modern humans. Research Dr Francois Balloux explains: "To test the alternative theory for the origin of modern humans we tried to find an additional, non-African origin. We found this just did not work. Our findings show that humans originated in a single area in Sub-Saharan Africa."

Source : Biotechnology and Biological Sciences Research Council