rysworld t1_j8pdyrr wrote

Something like more than 95% of the DNA of any given modern chihuahua is post-columbian. There was an ancient breed called a chihuahua, and then there was another breed later made to look kind of like them.


rysworld t1_j21i80h wrote

You will gain fat if you eat a calorie

If you work out quite a bit but still eat an excess- consider as an example the novice sumo wrestler, eating 5000 kcals a day and expending 4000- you will gain mostly subcutaneous fat, or fat under your skin. This isn't completely harmless, but generally the effects detrimental to you are limited to a little bit of inflammation and a strain on your joints like knees and hips, which are only "engineered" to take a certain amount of weight.

If you are not working off a lot of those calories constantly, you will start to accrue fat around your organs, which is much worse for you. Your organs will have to work much harder to do their jobs in the middle of all that fat, and you will start to edge towards lipotoxicity as your body struggles to deal with free fatty acids, which seems to play at least partially a causative role in all sorts of nasty diseases, including the insulin resistance that leads to diabetes.


rysworld t1_j21dbyy wrote

You have a couple of recent posts which are of a much more rambly and long bent than your usual style, with a different tone to the writing and less capitalization and grammar errors. Have you been using AI to write your recent posts? Please don't do that on a place where people are trying to get actual answers like ELI5.


rysworld t1_ir7q7ds wrote

There is genetic evidence extant in the genomes of large populations of humans and in DNA we have been able to extract from Neanderthal remains:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4072735/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2860157/

It is also notable that while there was SOME genetic input from Neanderthals into the modern human genome, there are no Neanderthal genes on any modern human Y chromosome- suggesting that it was either impossible for male Neanderthals and female modern humans to breed at all or that any such offspring produced were sterile like mules- a genetic block to fully interbreeding that points to a genetic basis to call them a different species.

We also have a lot of examples of modern human remains that have spent time in a wide variety of conditions, and none of them seem to deform in ways that give them the morphological characteristics of Neanderthals.