Free The Incredible Human Journey by Alice Roberts

grubs of warbleflies, which lay their eggs under reindeers’ skin.
     Later that afternoon, I watched three Evenki women, Valya, Tanya and Zoya, making reindeer boots from a prepared skin. They
     chose the fur from the legs of the reindeer to make the upper part of the boot, and sewed together patches from the reindeers’
     feet to create the soles. The sewing thread was also from the reindeer – long fibres pulled from a dried ligament.
    The finished boots were both pieces of art and functionally formidable. It seemed amazing that these relatively simple fabrications
     could outperform my Baffin boots – but they did. Reindeer fur provides fantastic insulation: there is an outer coat of long
     guard hairs, and dense under-wool next to the skin. The guard hairs contain cells with such large air spaces within them that
     they appear to be hollow under the microscope – and this is what makes reindeer fur so effective. 6
    The meat from the slaughtered reindeer was swiftly converted into dinner. Marina was very sanguine about the slaughter.
    ‘Whoever likes the blood can drink it,’ she said. ‘The liver is also good hot, and you can eat the eyes, which are delicious
     and good for you. We always eat the raw brains – they’re very tasty and healthy, too.’
    Meals with the Evenki consisted of a lot of reindeer meat, mostly boiled, with the water forming a sort of fatty, reindeer
     broth. Sometimes there were also bowls of chopped reindeer fat and, once, a bowl of pieces of frozen reindeer milk. I was
     lucky in that there was also some bread, small triangles of processed soft cheese in foil wrappers, and bowls of bon bons
     (which I suspect were laid on for guests). I had brought some packet meals with me, and the Evenki looked on in mild disgust
     as I poured boiling water into these concoctions. One of the children was brave enough to try some – and the other children
     ran away from him, screaming.
    The meat-rich diet of the Evenki seems somewhat bizarre and unhealthy from a Western perspective, but there’s evidence that
     it’s just what the Evenki need in their extreme environment. Our bodies produce heat all the time, as a by-product of metabolism,
     and the Evenki have been found to have a very high metabolic rate, probably due to high levels of thyroid hormones. A study
     of thyroid hormone levels in the Evenki suggested that there was a correlation with total energy and protein intake. A high
     proportion of the Evenki’s energy intake came in the form of protein and fat, not surprising given their reindeer-rich diet.
     It seems that eating a lot – in particular, a lot of meat – may spur the thyroid gland into producing more hormones. The result: raised metabolic rate and heat production. It’s as
     though the body is so well supplied with fuel that it can afford to ‘waste’ some as heat – except that, in northern Siberia,
     that ‘wastefulness’ is itself important to survival. 7 , 8
    A diet like the Evenki’s should set the heart disease alarm bells ringing, but, in spite of their meat-rich diet, the Evenki
     appear to have paradoxically low levels of ‘bad cholesterol’ in their blood. There are probably a number of reasons for this,
     including a genetic predisposition to low cholesterol, a high metabolic rate and a physically active lifestyle, all of which
     should help to keep ‘bad cholesterol’ down. Studies of other northern indigenous people have also shown strangely low rates
     of heart disease; a high consumption of fish containing omega-3 fatty acids may also play a role. However, very sadly, there
     have been recent reports of rising rates of heart disease in Siberian and Alaskan natives, as they move away from traditional
     lifestyles. The modern lifestyle diseases of heart disease and diabetes are spreading into the far north. 9

    That night, Marina and her two children shared the tent with me. There was plenty of room; we slept close to the edges (but
     not too close as