As a farmer’s son I know that the blood temperature of our pets such as horses, cows, pigs, etc.. is almost identical to that of humans and is about 37 degrees. However, this is not only valid for our pets but also for all mammals. Hence the following questions : a) Why is this ? and why more or less exactly the 37 degrees? b) The ambient temperature is usually lower than the temperature of our blood, which means that we eat a lot of calories (ie eat) to keep our body at the right temperature. An enormous saving in this calorie consumption could be caused if the temperature of our body and also of the mammals would be more variable and keep pace with the ambient temperature. Example : suppose – the ambient temp. 10 degrees, then body temp. eg 20 degrees.: – the ambient temp. 25 degrees, then body temp. eg 35 degrees The question is therefore : why have we not evolved according to this method ?
Answer
All our life functions, such as muscle function, digestion, brain function, etc., are determined by the metabolism in our cells. The metabolism consists of hundreds of biochemical reactions that are catalyzed by enzymes. These are specialized protein molecules whose function depends on factors such as temperature. The higher the temperature, the better the enzymes can work, and therefore the more efficient the biochemical reactions of our metabolism. But if the temperature reaches 40°C or more, the enzymes completely lose their effect. So the optimum “operating temperature” for our enzymes is around 37°C. Compare it a bit to an internal combustion engine, if it’s too cold it won’t work efficiently, and if it’s too hot it won’t – it has an optimal operating temperature.
This is actually the case for almost all other living things, including bacteria, the simplest of organisms. Bacteria grow best at about 37°C. Yeast cells eg too – that’s why bread dough rises better when it is warmed up (but not more than 40°C, because then the fermentation also stops).
Mammals and birds have evolved in such a way that they put a lot of energy into maintaining a constant body temperature. As a result, their metabolism always works in optimal conditions. As a result, they can move very actively, even fly, digest food quickly, develop higher brain functions.
In the scenario you are proposing, we would have a slower, less efficient metabolism at an ambient temperature of 10°C and a body temperature of 20°C. As a result, we would move more slowly, be no longer capable of great efforts, digest our food much more slowly, and no longer be able to think clearly. That’s what happens to reptiles like lizards, which are cold-blooded: they huddle in the sun or on a warm rock to raise their body temperature and activate their metabolism, or else they have to crawl into a crevice and wait for it to get warmer outside. is becoming. However, mammals and birds can be very active at all times, including at night when it gets colder, in bad weather or in winter, in cold areas where reptiles cannot live. And they can run, jump, fly, etc. for much longer thanks to their ever-active metabolism made possible by a constant optimum operating temperature for the enzymes.
Answered by
Prof. dr. dr. Luc Bouwens
Biomedical Sciences
Avenue de la Plein 2 1050 Ixelles
http://www.vub.ac.be/
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