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Survival of the weakest?
Define physical strength as a measure of the ability to exert force with your muscles.If the physically stronger individual is more likely to pass on their genes to their children relative to a physically weaker individual, then why are we, on average, physically weaker than our ancestors?The same question goes for cardiovascular fitness
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If we're physically weaker than our ancestors it's probably because we don't do as much physical exertion as they did. The same reason people that go to the gym are stronger than people that don't. Except instead of going to gyms, earlier generations did a lot more physcial labor.
However, I don't know any evidence that we could make generalisations about being less strong than earlier generations. For example it's a fact that people's hieghts have gone up in the last 100 years, due to being better nourished.
Anyway, there is no rule that says the physically strongest are bound to leave more offspring than others necessarily. It all depends on what, in a given environment, makes people more likely to survive, more likely to find a mate, more likely to raise children, more likely to see those childten survive, thrive, and have children of their own.
In human communities, physical strength doesn't necessarily have the biggest bearing on survival chances. Being intelligent, being valued by the community, being hard-working etc might well have a bigger impact.
However, I don't know any evidence that we could make generalisations about being less strong than earlier generations. For example it's a fact that people's hieghts have gone up in the last 100 years, due to being better nourished.
Anyway, there is no rule that says the physically strongest are bound to leave more offspring than others necessarily. It all depends on what, in a given environment, makes people more likely to survive, more likely to find a mate, more likely to raise children, more likely to see those childten survive, thrive, and have children of their own.
In human communities, physical strength doesn't necessarily have the biggest bearing on survival chances. Being intelligent, being valued by the community, being hard-working etc might well have a bigger impact.
Lifestyles has changed dramatically. We aren't obligated to walk long distances, plow via horse or ox, bring in the wood or coal, etc. Physically demanding jobs are often automated. Survival now depends on having foresight to find appropriate places to live, make choices about what to buy for food and clothing, and finding a job to provide the means to make a living.
I believe physical strength has less to do with survival now. Knowledge, wealth, and other assets may be more significant factors for current lifestyles.
If we are able to become less fit than our ancestors - and I question this - I would attribute it to beginning demanding physical labor beginning early in life and continuing through for as long as possible. Physical strength is as much nurture as nature.
I believe physical strength has less to do with survival now. Knowledge, wealth, and other assets may be more significant factors for current lifestyles.
If we are able to become less fit than our ancestors - and I question this - I would attribute it to beginning demanding physical labor beginning early in life and continuing through for as long as possible. Physical strength is as much nurture as nature.
source(s):
Genealogical studies
Genealogical studies
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The point is not that physical strength has the biggest bearing on survival chances. The point is, it does have an effect. Despite that, we have become weaker and less cardiovascularly able than our ancestors. The question is, why have we become weaker and less cardiovascularly fit despite this?
Athletic records have been broken ever since they were invented, average heights, body size etc are up.
About your second comment, I'm saying the opposite of the fact that if X has a bearing on survival it should always increase. My counterexamples are our physical strength and cardiovascular ability. My question is, why is that true? If it's an issue of trade-offs, then what are the trade-offs? If it's something else, then what is it?
When something sounds unbelieveable, 80% of the time it's because some populariser took selective bits that sounded interesting out of a study they didn't properly understand.
As for things always going in one direction... selection doesn't happen on one trait in isolation, but on the whole package. Wolves can evolve into foxes, because that works better in a different environment. Birds might generally become better fliers over time, but some also become flightless.
Flight is a perfect example of something that is costly, and not worth the cost in some environments.
Physical strength also has a cost, which is why your body builds muscle just where you've shown you need it not all over the body for the hell of it.
On top of all that, in a given species, it's perfectly normal for there to be different subgroups following different strategies. Big and strong vs smaller and more agile, aggresive alpha vs submissive follower etc.
If you are actually interested in finding the answer rather than being right about your pet theory, it'll be easy for you to find the explanation.
If you are keen to believe what you want to believe, obviously no-one will ever convince you.