Final Report Summary - ADAPT (Adaptation, Dispersals and Phenotype: understanding the roles of climate, natural selection and energetics in shaping global hunter-gatherer adaptability.)
Our species, paradoxically, has both high levels of observable variation and low levels genetic diversity. Understanding the mechanisms which drive human biological variation remains one of the significant challenges in Anthropology and was the principal focus of the ADaPt project. To test this, we conducted two major studies, the first investigated the pattern of human variation displayed in archaeological skeletal remains from around the world over the past 20,000 years. We analysed this data relative to variation in climate, to better understand the influence of the environment on the diversification of our species. In the second study we analysed human athletes participating in ultra-endurance events to understand the functional significance of human variation when humans are pushed to their physical limits in different environments.
Our research in the first study demonstrated that climate shaped the biology and some aspects of the culture of our ancient ancestors, but that we tend to adapt to environmental stress in ways that are different to other species. More specifically, since our common origin within Africa, humans encountered many extreme environmental stresses, and these shaped the biology of human populations as we dispersed into different environments around the world. Behavioural and cultural variation helped to lessen these environmental stresses and their impact on our biology, meaning that there are many other influences on the observable variation within our species. This can be observed in the environmental influences on different regions of the human body, with the skull being primarily influenced by neutral genetic variation and buffered from environmental stress by cultural mechanisms, while the bones of the human limb are strongly influenced by local environmental stress.
Within the second project we studied the biological consequences of chronic energy deficits that are associated with sustained high levels of activity in diverse environments. We demonstrated that, under these conditions, our bodies prioritize available resources towards specific short-term physiological and cognitive mechanisms essential for survival, at the expense of mechanisms that are essential over longer time frames. This provides evidence that subtle variation in the human body, such as the proportional length of limb segments, or the short-term regulation of hormones, or performance in different cognitive domains, have energetic and survivorship consequences when we are under physical and environmental stress. This evidence provides a way to infer selective pressures that may have shaped the success of our species over broad evolutionary timescales. As a component of this research we have investigated the factors that influence the strength of bones in the human skeletons. We demonstrated that the pattern and magnitude of activities such as running or rowing, influence the strength of bones. By comparing the bone strength of living humans with known patterns of behaviour to our prehistoric ancestors, we can better understand patterns of human activity in the past. The results of this component of our research have demonstrated consistently high levels of activity among women in prehistoric Europe and has helped us to better understand patterns of mobility in the human past.
Our research in the first study demonstrated that climate shaped the biology and some aspects of the culture of our ancient ancestors, but that we tend to adapt to environmental stress in ways that are different to other species. More specifically, since our common origin within Africa, humans encountered many extreme environmental stresses, and these shaped the biology of human populations as we dispersed into different environments around the world. Behavioural and cultural variation helped to lessen these environmental stresses and their impact on our biology, meaning that there are many other influences on the observable variation within our species. This can be observed in the environmental influences on different regions of the human body, with the skull being primarily influenced by neutral genetic variation and buffered from environmental stress by cultural mechanisms, while the bones of the human limb are strongly influenced by local environmental stress.
Within the second project we studied the biological consequences of chronic energy deficits that are associated with sustained high levels of activity in diverse environments. We demonstrated that, under these conditions, our bodies prioritize available resources towards specific short-term physiological and cognitive mechanisms essential for survival, at the expense of mechanisms that are essential over longer time frames. This provides evidence that subtle variation in the human body, such as the proportional length of limb segments, or the short-term regulation of hormones, or performance in different cognitive domains, have energetic and survivorship consequences when we are under physical and environmental stress. This evidence provides a way to infer selective pressures that may have shaped the success of our species over broad evolutionary timescales. As a component of this research we have investigated the factors that influence the strength of bones in the human skeletons. We demonstrated that the pattern and magnitude of activities such as running or rowing, influence the strength of bones. By comparing the bone strength of living humans with known patterns of behaviour to our prehistoric ancestors, we can better understand patterns of human activity in the past. The results of this component of our research have demonstrated consistently high levels of activity among women in prehistoric Europe and has helped us to better understand patterns of mobility in the human past.