Today is the installation day for a new exhibition in the Anatomical Museum at Edinburgh University looking at Colonising Mars. Our team looked at anatomical changes.
Here is our piece – Life on Mars with David.
Let me start by acknowledging that David was carved as a white man and we are meant to be decolonising everything but we went with David – despite the known issues about proportions and it being carved so that it looked correct when viewed from below – because it was easier to show a colour change and we had a pop culture reference to address.
Also acknowledging the words of the evolutionary anatomist we consulted that ‘trying to predict evolution changes is an exercise in futility’ – view the piece as a conversation starter.
Also – selection pressure isn’t really a thing anymore as we do not allow the weakest in society to die (quite rightly). It is no longer an evolutionary advantage to have certain physical traits.
All that been said – What did we change?
Height – The gravity on Mars is 38% of that on Earth. It is the resistance to gravity that gives our bones their strength. Bones lose up to 5% of their mineral density per month of space flight. The reduced gravity would lead to more fragile bones and hence increase the likelihood of fractures. We thought we would address this by developing a stockier frame to protect against fractures.
Head size – as bone fractures are more likely we thought that birth would be more likely to proceed by C section. There is a debate that it is the passing through the birth canal that limits the size of the human head. With this restriction gone, head size could increase. (Mitteroecker, P. et al (2016) cliff edge model of obstetric selection in humans PNAS,113(51))
Eye size – the light on Mars is the equivalent to a cloudy day on Earth. The adaptions that the eyes might make would probably all be internal but that doesn’t work on a model, so we made the eyes bigger.
Skin – the annual exposure to radiation is greater on Mars – 30 millisieverts as opposed to 3. For some reason all of the people discussing colonising mars have increased the pigmentation in the skin with carotenoids rather than melanin. We couldn’t find out why but increased the orange colour to fit in with the prediction that skin pigmentation would increase.
Spleen – we developed a bulge on the left to indicate a larger spleen. We based this on research on the Bajau people who spend a lot of their time free diving. These people have larger spleens. Upon exposure to an oxygen restricted environment- part of the divers response, the spleen pushes a large volume of red blood cells into the circulation so that the breath can be held for longer. We thought there would inevitably be some sort of breach of the containment on Mars and so the ability to hold the breath for a longer time might be helpful and might actually be a genuine evolutionary selection criteria. (Trenkman,M. (2018) A breath holding adaptation. Nature Review Genetics 19.)
Limb circumference – some of our body shape is due to the distribution of fluids within our tissues. This is affected by gravity and so a reduced gravity would redistribute our fluids. According to NASA the circumference of the leg can reduce by 30% during space flight (sitn.hms.hardvard.edu/flash/2013/space-human-body/). We wanted to reflect this effect and so reduced limb circumference and removed the chiseled abs.
We hope it starts a conversation and maybe makes people aware of what parts of their bodies’ do and why they are like they are.