Institute of Cognitive and Evolutionary Anthropology, University of Oxford, Oxford, UK.
Biol Lett. 2012 Feb 23;8(1):90-3. doi: 10.1098/rsbl.2011.0570. Epub 2011 Jul 27.
Ambient light levels influence visual system size in birds and primates. Here, we argue that the same is true for humans. Light levels, in terms of both the amount of light hitting the Earth's surface and day length, decrease with increasing latitude. We demonstrate a significant positive relationship between absolute latitude and human orbital volume, an index of eyeball size. Owing to tight scaling between visual system components, this will translate into enlarged visual cortices at higher latitudes. We also show that visual acuity measured under full-daylight conditions is constant across latitudes, indicating that selection for larger visual systems has mitigated the effect of reduced ambient light levels. This provides, to our knowledge, the first support that light levels drive intraspecific variation in visual system size in the human population.
环境光照水平影响鸟类和灵长类动物的视觉系统大小。在这里，我们认为人类也是如此。光照水平，无论是到达地球表面的光量还是昼长，都会随着纬度的增加而降低。我们证明了绝对纬度和人类眼球体积（眼球大小的指标）之间存在显著的正相关关系。由于视觉系统成分之间的紧密缩放关系，这将转化为在更高纬度地区扩大视觉皮层。我们还表明，在全日光条件下测量的视力在整个纬度范围内保持不变，这表明为了更大的视觉系统而进行的选择减轻了环境光照水平降低的影响。这在我们的知识范围内首次提供了支持，即光照水平驱动了人类群体中视觉系统大小的种内变异。
