# how would humans evolve?

what would happen if 50,000 humans were sent to a planet that has 3 times gravity, in a arid like environment.Through unknown means. The planet has a similar atmosphere to our own and the air is completely breathable. The humans starting location would be nearby a place with hily area yet few wildlife except small herbivores live there.Then leaving them to there own devices for 5000 years. assuming they dont die of disease, or anything else. What would these humans be like afterwards?

• I would like more detail. – The Daleks Jan 25 '20 at 23:45
• 500 hundred years? 50,000 years you mean? – Double_S Jan 25 '20 at 23:55
• 5000 years I dont why i typed that but i fixed it – neo flare Jan 25 '20 at 23:56
• 5g inhabit blood flow to the brain, 4g is expensive and poor coverage and 3g still lag like hell... you sure u want 3g on that planet? – user6760 Jan 26 '20 at 1:23
• to late to change now >//< and should change it too 2 g or something – neo flare Jan 26 '20 at 1:27

We have 50.000 humans. All of them are supposed to be healthy on earth.

Now, they land on the superplanet. The planet has about 3 times the mass to earth to get 3 times the gravitational pull. Mass is proportional to Volume, so Volume is almost factor 3. That gives $$V_P=3 V_E=3\times 4/3 \pi \times r_E^3=4/3\pi\times r_P^3$$ which can be simplified into $$r_P=(3r_E^3)^{\frac 1 3}=3^{\frac 1 3}r_E$$. That's about 1.44 earth radii.

## Reality Check

Shortly after the landing, casualties mount as they stumble and fall in the extreme gravity, breaking their neck bones within the first month. Let's say 1 in 10 dies from such accidents. But the longtime effects stay. Of the remaining 45.000 people, roundabout 2 of 3 will die from related bloodpressure failures, aneurisms, water gathering in their lungs and similar over the next year. The rest will succumb within the following 5-10 years to similar reasons.

## Ignoring that they should have died...

If you ignore that they should have died out withion their first decade after landing, their genetics will be very much the same as those of the landing people after 5000 years. Why? Humans didn't change a lot in the last 5000 years. Evolution is known to be the really really long game. Think not in term of years, think in generations. 5000 years for humans are... let's say about 250 generations. That's pretty much nothing for regular evolutionary times.

### the long game explained

It took Earth 3.2 million years to get from Australopithicus afarensis to Homo sapiens. During those, Earth had a phase of about 600.000 years, in which it refined Homo habilis into Homo erectus which left Africa. About 700.000 years ago, H. erectus was surpassed by Homo heidelbergensis and it took another 400.000 years for Homo sapiens to emerge.

### But...pressure?!

Humans snatched dogs about 50000 years ago and started domesticating them. They controlled their evolution. Dogs can reproduce after about 5 years. Those 50.000 years are maybe 2500 generations of Human but 10.000 generations of dog facing much more radical selection.

250 generations of normal evolution are nothing. With extreme conditions and a regulatory body that decides who gets to have a child, it might work, but 3g for 1g adapted humans still should be pretty much a fully lethal environment.

## Different conditions?!

Let's say we get a planet that just generates 2g. Then our humans still have a very high mortality rate after landing, as blood pressure isn't all deadly but their brain gets a permanent malnutrition and they have to lumber around another time their own body weight. It's somewhat more believeable than 3g though. Borderline feasable (I would put 1.5g as the limit what humans could do with out body structure).

Now, let's give them both more time and more people to survive the initial mass death on this high gravity world and a chance to evolve... or we give them medical equipment to alter genetics and a society that culls non-adaptive traits. Let's not exactly specify either.

### Newmen

Now, how do these Newmen look? First of all, their bodys are built sturdy, the bones thicker than Human anatomy. They also are shorter, usually maxing out at around 1600 mm for tall specimen and averaging around 1400 mm. Their muscles are much more pronounced, averaging their BMI to around 35 for what would be their healthy weight.

In regards to arid adaption, Humans are actually already capeable of living in arid environments, so other than a preference of darker skin coloration, not much needs to change. Possibly their ears are larger to vent the extra heat that they can't get rid of due to their more sturdy bodies. They might not gather fat in the way Humans do, as extra fat would result in overheating. In some ways... The Newmen are dark skinned, muscled but not fat dwarves.

This all comes at a price though: Their brain doesn't get supplied with the same ammount of blood as compared to human brains, and thus might be somewhat less developed. If measured by Human IQ-tests where the average human would reach the 50-percentile mark (half of the people in the room are smarter, half are dumber), Newmen do, on average, only reach around the 40-percentile mark. That does not mean that Newmen are dumb, they still might reach similar genius levels, but that the average Newman would have an IQ some points below the average human. As human IQ is supposed to be a bell-curve around 100, Newman IQ would, on the same scale, be slightly shifted to the left, possibly centering around 90 to 95.

• Not saying you are wrong, but if of those 50.000 you said would die only 100 people would survive, because of some magical... i mean genetical trait that make them able to survive, then this trait would pretty much be certain for every child in the second generation. This COULD accelerate evolution a lot. – PSquall Jan 26 '20 at 0:56
• @PSquall if only 100 survive, there will be no fourth generation because it will be too inbred. Some 50 years ago, people stated a 50/500 rule, which became the Minimum Viable Population: "For Humans, including the desire to ward of genetic defects due to inbreeding the median MVP reported is 4,169 individuals." – Trish Jan 26 '20 at 1:03
• lets say a reasonable big number to of people survive to reduce that factor. I think there was a paper that said 160 people, but specifically chosen to be highly genetical diverse. – PSquall Jan 26 '20 at 1:03
• @PSquall even if 5k people survive, 5k years are not enough to get evolution done unless you cull any individual that doesn't show the desired traits. Which, because of how human reproduction works, ensures that the F1 falls under the needed MVP and makes likewise sure that F4 will not come to be. – Trish Jan 26 '20 at 1:05
• @Demigan It is. Armadillos had their brain de-evolve from more powerful ones to ones that can run on low oxygen for some 7 minutes. – Trish Jan 26 '20 at 13:49

3 times earths gravity

This is feasible, we as a species look for planets that usually are 3 to 4 times earths gravity, and if we are talking about 50000 buff people, then yeah. However, this won’t come without physical changes, a lot can happen in 5000 years and with enough time, your humans would look a bit smaller than the average human, like dog to probably cat size. ( not that accurate to how small they actually will be )

arid like environment

So, this one is a bit tricky, many species have evolved many different ways to survive the arid environments, but let’s look at some of our characteristics and adapt them to a more arid like environment. Heat, if they brought technology on the planet then they could simple build air conditioners or build underground, but if not, then they will probably evolve a thick coat of fur to protect themselves from the sun and wide soft feet to withstand the hot surface. Water, now, if we are your talking about, rains only a few times, has a few lakes, and e.t.c, then they could evolve by either needing very little water to survive ( unlikely ), or they could evolve to store water, much like camels.

** starting location is hilly area and a few small herbivores**

Now, food will need to be preserved some how, and like I said, if they brought technology with them, then this would be easy, but if not, then ones with a low metabolism would most likely survive the longest because that means that they can burn fewer calories in order to function and store the rest as fat. Building near hilly areas will be great for them, because in order for every person to essentially withstand such gravity, they would need to be well fit, and sense there near hilly areas, this will allow them to Exercise better by building endurance, strength and speed.