Let's talk about… Biology

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  • #25995
    Shiv
    Participant

    I’m creating this thread as a “follow-up” to the Introduction one because talking endlessly about exciting and unanswerable questions is awesome. (And that way, people can actually introduce themselves on the Introduction topic 🙂 ).

    In the Introduction thread, Kenna asked about the one question in the field of science that we’d like to see answered, and I talked about the observation that “bigger organims live longer”, wondering about the biological basis of this.

    We’ll start with this topic because I’ve been itching to reply to what Kenna said:
    “Could it be that larger organisms survive telomerase shortening/cell aging better because they have more cells? “.

    The problem is that ‘bigger animals have more cells’ implies more cell divisions so it would increase the issue of telomere shortening in bigger organisms, as it is related to the number of cell cycle, and it would not explain the lenghtening in lifespan :/.

    A link with metabolism is highly probable. An older observation (see Kleiber’s law) is that although bigger animals use more energy than smaller ones, the increase in metabolic basal rate is less than the increase in size i.e. larger animals need less energy per kg of body weight than smaller ones, maybe because a lesser weight mean more structural tissue and less reserve tissue.

    I’ll be curious to hear what you think before going any deeper.

    #25998
    Kenna
    Spectator

    Interesting premise. While the relationship between size and metabolism doesn’t hold true for all organisms (endoliths, as an extreme example), it is somewhat reliable. However, I am doubtful that it works as a unified theory. There are many things which may affect aging, from stress to UV rays to free radicals working in conjunction with oxygen toxicity.

    The longest living animals in the world tend to be aquatic. Whales are quite large and have few predators. Far less than any mouse, anyway. With more predators comes more stress. This probably has a significant effect on telomerase shortening. They also tend to be less exposed to UV rays than terrestrial animals. And lastly, just as another possible, small creatures have very high respiration rates. Could not free radicals be formed more quickly because of this?

    #27193
    Meadow Rain
    Spectator

    Glad you brought this up and although this might not correlate directly to your subject l love nature trees animals , pond life.etc… and l consider myself a naturalist and not nerdy at all…..l think.
    Also l was sent a picture of a very simplistic mini octopus that is vertually immortal.
    I will try to send the picture somehow.

    • This reply was modified 5 years, 7 months ago by Meadow Rain.

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