humans

[sci-man]

humans have evolved to be soft-skinned have no way to defend themselves (claws horns, etc.) and we cant climb trees like monkeys we don't blend into our environment the only good thing is that we are smart and barely even that anymore considering whats going on in the world so why did we evolve like this and only us 

[Phi for All]

18 minutes ago, sci-man said:

humans have evolved to be soft-skinned have no way to defend themselves (claws horns, etc.) and we cant climb trees like monkeys we don't blend into our environment the only good thing is that we are smart and barely even that anymore considering whats going on in the world so why did we evolve like this and only us 

Birds give up a lot in order to fly. They have almost no muscle that doesn't go into flapping their wings, to the point where they can't even swallow water normally. They've learned to take liquids into their mouths and then move their heads up quickly using wing muscles to force it down their throats.

In a similar way, we've given up a lot to develop complex intelligence. You shouldn't say we're "barely even that anymore" just because we're finding it increasingly difficult to integrate all our strengths and capabilities as our population grows and our cooperative nature is tested. We're probably smarter than we ever have been, and we've filled a niche no other animal has. There are other animals who fill a place in their environments no other creature fills, so try to think of it that way.

Why we evolved like this is more of a philosophy question.

Why only us? It seems reasonable that we'd eliminate any competition to our high intelligence just by being more successful. 

[swansont]

28 minutes ago, sci-man said:

why did we evolve like this and only us 

Why would you expect more than one species per niche?

[zapatos]

44 minutes ago, sci-man said:

humans have evolved to be soft-skinned have no way to defend themselves (claws horns, etc.) and we cant climb trees like monkeys we don't blend into our environment the only good thing is that we are smart and barely even that anymore considering whats going on in the world so why did we evolve like this and only us 

We are also comparatively large. When you step out your door, how many species are out there who can kill and eat you?

[Ten oz]

1 hour ago, sci-man said:

humans have evolved to be soft-skinned have no way to defend themselves (claws horns, etc.) and we cant climb trees like monkeys we don't blend into our environment the only good thing is that we are smart and barely even that anymore considering whats going on in the world so why did we evolve like this and only us 

Edible Frogs have soft skin and lack horns or claws to protect themselves. Humans are also excellent tree climbers, have you ever seen a horse get up a tree? Humans are considerable more capable than you imply. Without tools humans are able to forage and/or kill a very large variety of food. With nothing more than our hands and feet we can pick fruits, dig up roots, collect eggs, shellfish, reptiles, insects, birds, and etc to eat.

[Phi for All]

14 minutes ago, Ten oz said:

Edible Frogs have soft skin and lack horns or claws to protect themselves. Humans are also excellent tree climbers, have you ever seen a horse get up a tree? Humans are considerable more capable than you imply. Without tools humans are able to forage and/or kill a very large variety of food. With nothing more than our hands and feet we can pick fruits, dig up roots, collect eggs, shellfish, reptiles, insects, birds, and etc to eat.

Good points. I find myself always defending high human intelligence, but versatility is also a successful trait. Tigers are bigger and fiercer than leopards, and could easily beat one in a straight-up fight, but leopards are much more successful hunters in their niche because of their adaptability. 

Defending yourself by running away is very successful, often more so than with tooth or claw. And intelligence can help you figure out how NOT to stand out in your environment like a sore thumb. Comparisons need to be taken in context.

[Endy0816]

Punches... thrown stones and wood... persistence hunting... herding animals off cliffs or into traps...

Even without many tools we can bring down almost anything.

[Ken Fabian]

An individual human may look like an easy meal to a large predator but humans come in groups and when they are angered - say by a predator taking one of them - then even large predators have cause to fear. An individual may seek safe refuge but a relentless group hunt to track and kill the culprit - and anything that looks like it - is the usual group response.

I do think those mostly unique to hominid capabilities - tools, communication, group organisation, problem solving abilities - overcome a lot of physical limitations. They don't just compensate but greatly overcompensate - to the extent that these become powerful aids that can turn a thin skinned, furless, slow running biped into the top predator in almost any environment.

 

Edited May 2, 2018 by Ken Fabian

[Bender]

Our skin is thick enough. Many insects and pathogens cannot pierce our skin. Thicker skin would reduce our agility and sense of touch, while it wouldn't help against predators who could easily pierce the thicker skin anyway.

 

[Sensei]

For a very long time, in human evolution, the only "predator" capable to hunt and kill other human, is other human..

 

[swansont]

5 hours ago, Sensei said:

For a very long time, in human evolution, the only "predator" capable to hunt and kill other human, is other human..

No, I think that's pretty obviously not true. Other large predators are capable of killing humans and do so even in modern times.

[NimrodTheGoat]

21 hours ago, sci-man said:

why did we evolve like this and only us 

Everyone forgets about the poor Neanderthals. 

[Doozel]

22 hours ago, sci-man said:

humans have evolved to be soft-skinned have no way to defend themselves (claws horns, etc.) and we cant climb trees like monkeys we don't blend into our environment the only good thing is that we are smart and barely even that anymore considering whats going on in the world so why did we evolve like this and only us 

Because " It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is most adaptable to change." and while developing more and more mental capabilities, we didn't need anymore claws, fangs or horns.

As it has already been said, we are well equipped to survive even in harsh conditions, but in terms of combat large predators obviously outclass us. Something interesting is that we are still very good at fighting other humans, for example our fists have evolved for punching (https://phys.org/news/2012-12-fine-fists-fury-evolved-dexterity.html), most likely to resolve conflicts or self defense.

[Sensei]

4 hours ago, swansont said:

No, I think that's pretty obviously not true. Other large predators are capable of killing humans and do so even in modern times.

But OP was asking about external influences on human evolution..

Think about it from perspective of probability. Every day somebody dies because of car crash, airplane accident etc. etc. Obviously genes present in dead person are gone (if dead person had no offspring, that's essential thing). But because it's just per mille of the all deaths, influence on evolution of human as a whole, is negligible.

On the other hand, death of at least 60 millions of people during II world war was not negligible for human evolution (e.g. decreased diversity of genes of Jews, Germans, Poles, Europeans).

What I wanted to say initially was that humans kill significantly much more humans than wild animals do it, so their influence on human evolution is much more stronger.

Accidentally you reminded me about one much more evolution influential thing - diseases, microorganisms and viruses..

[HB of CJ]

Humans evolved to be just good enough.  Not extraordinarily good.  Not exceptionally bad.  A fair turn of speed.  Excellent endurance.  Good enough eyesight.  Hearing.  Some sense of smell.  A very big brain.  Plus the important thing you need to remember about humans is that they always run in packs.  One human alone was weak.  Fifty together were superior.

What is also important is that at the time Humans really got going there was nothing else standing in their way.  All the environmental conditions were ripe.  Humans had the vital capacity to quickly adapt to a changing environment.  The final factor was that people learned to adapt the environment to their needs rather than just blending in.  The rest is history.

[Ten oz]

30 minutes ago, HB of CJ said:

Humans evolved to be just good enough.  Not extraordinarily good.  Not exceptionally bad.  A fair turn of speed.  Excellent endurance.  Good enough eyesight.  Hearing.  Some sense of smell.  A very big brain.  Plus the important thing you need to remember about humans is that they always run in packs.  One human alone was weak.  Fifty together were superior.

What is also important is that at the time Humans really got going there was nothing else standing in their way.  All the environmental conditions were ripe.  Humans had the vital capacity to quickly adapt to a changing environment.  The final factor was that people learned to adapt the environment to their needs rather than just blending in.  The rest is history.

I disagree with this. Humans are not "just good enough". Prior to creating agricultural and large civilizations Humans spread out and successfully inhabited every continent on earth. Humans have very high level of dexterity. Thumbs and ball & socket joints are every bit useful as fur, sharp teeth, horns, or etc. The diversity of our diet, what we can eat, is/was also a major evolutionary advantage. Our dexterity and diets allow(ed) us to eat food collected from underwater up to food located atop trees. Human also have tremendous endurance and mobility. We can cover very large amounts of ground in a day. Our eyesight has depth and is in color. That is much better than merely "good enough". A lot of animals have poor color vision and depth. The list goes on and on. Humans are excellent swimmers, we are able to vocalize (trick prey or intimidate predators), we are naturally great at carrying things thanks to being bipedal, and etc, etc, etc.

[Phi for All]

7 minutes ago, Ten oz said:

I disagree with this. Humans are not "just good enough". Prior to creating agricultural and large civilizations Humans spread out and successfully inhabited every continent on earth. Humans have very high level of dexterity. Thumbs and ball & socket joints are every bit useful as fur, sharp teeth, horns, or etc. The diversity of our diet, what we can eat, is/was also a major evolutionary advantage. Our dexterity and diets allow(ed) us to eat food collected from underwater up to food located atop trees. Human also have tremendous endurance and mobility. We can cover very large amounts of ground in a day. Our eyesight has depth and is in color. That is much better than merely "good enough". A lot of animals have poor color vision and depth. The list goes on and on. Humans are excellent swimmers, we are able to vocalize (trick prey or intimidate predators), we are naturally great at carrying things thanks to being bipedal, and etc, etc, etc.

Excellent points. We're a package deal. You have to look at all the resources we have to fully appreciate humans. 

And if we make big mistakes, that's how we learn big things. Hopefully we can apply our intelligence using what we learned to fix what we broke.

[swansont]

4 hours ago, Sensei said:

But OP was asking about external influences on human evolution..

Think about it from perspective of probability. Every day somebody dies because of car crash, airplane accident etc. etc. Obviously genes present in dead person are gone (if dead person had no offspring, that's essential thing). But because it's just per mille of the all deaths, influence on evolution of human as a whole, is negligible.

On the other hand, death of at least 60 millions of people during II world war was not negligible for human evolution (e.g. decreased diversity of genes of Jews, Germans, Poles, Europeans).

What I wanted to say initially was that humans kill significantly much more humans than wild animals do it, so their influence on human evolution is much more stronger.

Accidentally you reminded me about one much more evolution influential thing - diseases, microorganisms and viruses..

The statement was wrong, and these influences you cite have only been present for a proverbial blink of an eye in evolutionary terms. War doesn't account for a large proportion. Before modern medicine, especially.

60 million in WWII is 12 million a year. Out of a population of 2.3 billion. What was the overall death total per year back then? 

[sci-man]

On 5/2/2018 at 1:35 PM, zapatos said:

We are also comparatively large. When you step out your door, how many species are out there who can kill and eat you?

a lot of species i can name about 50 now

[zapatos]

1 minute ago, sci-man said:

a lot of species i can name about 50 now

Given that there are believed to be eight or nine million species on earth, you've got a long way to go before you can show our comparatively large size is not a major asset when defending ourselves.

[sci-man]

2 minutes ago, zapatos said:

Given that there are believed to be eight or nine million species on earth, you've got a long way to go before you can show our comparatively large size is not a major asset when defending ourselves.

i said now not in  my overall research just now and tiny baby rattlesnakes can kill multiple elephants with one bite and would have no problem taking us down meaning our size does not matter

Edited May 7, 2018 by sci-man

[zapatos]

3 minutes ago, sci-man said:

i said now not in  my overall research just now and tiny baby rattlesnakes can kill multiple elephants with one bite and would have no problem taking us down meaning our size does not matter

Yes, I know. Let me know when you hit half a million.

Quote

tiny baby rattlesnakes can kill multiple elephants with one bite

Citation?

[CharonY]

55 minutes ago, sci-man said:

i said now not in  my overall research just now and tiny baby rattlesnakes can kill multiple elephants with one bite

That would be quite a feat, as rattlesnakes are native to the Americas. You know, the continent where you generally do not find elephants. Even then, adult rattlesnakes have fangs up to ~15 mm which would not even pierce most of the elephant's skin, especially around the legs. The most venomous ones have fangs about half that size.

But even if we assume a direct injection in a vunerable of the most lethal rattlesnake venom, we would need ~0.03 mg/kg to reach LD50 (i.e. concentration where 50% of injected mice die). For subcutaneous injection (which arguably would be more likely) we would go an order of magnitude higher. Of course these are only approximations, as the scale is massively different from the models for LD measurements, but it is the closest we can get.

If we take the smallest elephants (African forest  elephant, Loxodonta cyclotis) at a weight of ~2,700 kg, we would need 81 mg to reach LD50. The total amount milked from e.g. the Mohave rattlesnake amounts to ~150 mg, so even if completely extracted we could at most inject two elephants with levels close to LD50 (and statistically one may die). Alternatively, a single lethal dosage for one elephant might be reached (though a bit difficult to tell as the these are not linear functions).

However, you specified per bite. Although the snake can adjust the dosage, the average bite delivers ~8% of the total stored venom, so that would bring us to ~12 mg. Enough to kill a human, but quite lower than the estimated LD50 for elephants.

Even worse, you specified baby rattle snakes, which have a much shorter fang and also far less venom, meaning that even fully milked they are likely unable to kill even a single elephant from the smallest available species (even with intravenous injection). So even under the most charitable assumptions it is fair to assume that the proposed "research" is quite inadequate. Not to mention that I have no idea what the purpose of the argument is. 

[Phi for All]

1 hour ago, sci-man said:

a lot of species i can name about 50 now

I think you're stretching your definitions to include cows, horses, and pigs. They may be capable of killing you and eating you (if they had nothing else), but they aren't generally a threat when you "step out your door", as zapatos put it.

[Moontanman]

4 hours ago, sci-man said:

a lot of species i can name about 50 now

 

Walking out my front door I could conceivably run into one animal that could kill and eat me within about 100 meters. Stretch that to around one kilometer and you might turn up one more. 

Killing me is another matter, within that same distance limit you might find three or more capable of actually killing me but not eating me. I'd like to know what species you are talking about and where you live so I can avoid that place. I live near a huge swamp, the animals capable of killing and eating me are alligators and black bears, the animals capable of just killing me are two species of rattlesnake, copperhead, cottonmouth, and very rarely a coral snake. Are you counting insects? 

How about a list of the dangers you might face?