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April 16[edit]

How can some birds have lifelong high core temperatures?[edit]

Understandably they need to be hot to fly well but something must be different. Protein differences? Sagittarian Milky Way (talk) 18:58, 16 April 2024 (UTC)[reply]

Some possible answers here. Mikenorton (talk) 19:21, 16 April 2024 (UTC)[reply]

How do chickens live for 5-10 years with average body temperatures of 105-107? With smaller breeds over 106. Sagittarian Milky Way (talk) 00:51, 17 April 2024 (UTC)[reply]

That article says a lot about how active birds are, but some are not terribly active at all. Eagles glide and soar with seemingly minimal energy input. Unless under threat (which is rare), Australia's large ratites spend the day strolling around or just sitting. Other Australian birds just seem to sit on tree branches all day, only very occasionally making a very short foray for food. HiLo48 (talk) 03:18, 17 April 2024 (UTC)[reply]

Their defense against pathogens is presumably dependent to some extent on maintaining high core body temperatures, or having very elevated temperatures in bursts like bats. Is a temperature difference of a few Celsius between us and chickens that much of a challenge for biological systems? Many social insects operate at much higher temperatures. Sean.hoyland (talk) 04:29, 17 April 2024 (UTC)[reply]

It depends on a lot of factors, but probably the biggest one is just whether enzymatic function can happen well enough at those temperatures. Not only is temperature an important factor in any equilibria or reaction rates (see reaction rate, Arrhenius equation, equilibrium constant, Van 't Hoff equation and Van 't Hoff plots, etc.) and are enzymes often quite pH dependent, which itself changes as a result of temperature, but at different temperatures the physical structure of enzymes, i.e. how they are folded and other structural issues, can change. This will denature the enzymes, potentially permanently, and a denatured enzyme either has incredibly reduced function or total even loss of function. That said, there isn't some magic one temperature that is best for all enzymes in nature. Rather, as a result of evolution and natural selection, the enzymes of a particular organism will be at their optimal temperature and pH range (or close enough to it for organism survival) for the given conditions of that organism. If you try to put human lysozyme in a chicken or a cat, it likely will not function. However, chickens and cats have their own versions of lysozyme which do work at their operating temperatures. Put chicken or cat enzymes in us, and they might not thermally denature, but they might not be at an optimal temperature for enzymatic activity (or worse, the direction of the equilibrium could even shift, depending on the thermodynamics involved). The adaptations needed to adjust enzymatic optimal temperature ranges often (but not always) aren't very complicated, to the point that a few degrees Celsius adaptation might only require a single point mutation changing one codon/one amino acid. However, even that can become a problem when you have a lot of enzymes needing to adapt to a very quickly changing temperature condition. Thus the problem with coral bleaching, for example. Not having a lot of temperature regulation and being dependent on external temperature, if a temperature shock happens too rapidly for generational/evolutionary adaptation, you start seeing bleaching and eventually extinction events (we have extensive fossil records of other temperature shocks that wiped out the vast majority of marine corals). --OuroborosCobra (talk) 14:53, 18 April 2024 (UTC)[reply]

An intelligent bird might just as easily ask "How can some mammals have lifelong low core temperatures?"

Everything is relative, and birds have been around something like 160 million years longer than H. sapiens, so their 'normality' is more established than ours. {The poster formerly known as 87.81.230.195} 151.227.134.31 (talk) 16:08, 17 April 2024 (UTC)[reply]

Their biochemical and enzymatic activity is optimized enough to that temperature for function. Same as any other living thing. --OuroborosCobra (talk) 17:26, 17 April 2024 (UTC)[reply]

There's been some studies which indicate there may be two phases of liquid water with a mixture from 50°C-65°C which is a major barrier to life evolving to work at a higher temperature. NadVolum (talk) 20:30, 26 April 2024 (UTC)[reply]

How did nobody notice that before? What happens between 50 and 65? Sagittarian Milky Way (talk) 13:05, 27 April 2024 (UTC)[reply]

I’m a bit dubious on this, at least in terms of the suggested implication of a barrier to life evolving to work at those temperatures. There absolutely are thermophiles that thrive at those temperatures (50-65 C) and beyond. They do require different enzymes, as I suggested in my reply above, that function efficiently at those temperatures. For most life, there isn’t any evolutionary pressure to evolve enzymes capable of such high temperature function as those conditions are pretty rare on Earth. Extremely hot springs and volcanic vents, sure, but not much else. I have a feeling the absence of such a pressure has a lot more to do with the lack of life at those temperatures than any barrier from supposed different liquid phases (especially given that liquid state water systems are constantly having molecules moving around and rearranging themselves around biomolecules through polar, hydrogen bonding, and hydrophobic interactions). —OuroborosCobra (talk) 21:08, 27 April 2024 (UTC)[reply]

I too want to see this paper. In the meantime, here's one on liquid-state polymorphism in supercooled water. Double sharp (talk) 18:15, 27 April 2024 (UTC)[reply]