Homo erectus | The Out of Africa Series

[@lee-be6pp]

It's a good question why our brains continued to grow regardless of environment. From what I know it's not because constraints were lifted or that meat was added to the diet of our ancestors. It's simply a matter of potentials; our DNA contained the possibility of large brains. The fact that our brain size increased proves that such potential was present in our ancestral forms. We can't say for certain that potential doesn't exist within current forms of other species but I'm pretty sure it doesn't. Reptiles appear to have reached their intellectual limit, though birds seem to have some endowment of progress still. And always remember: Elephants evolve much faster than mice.

[@xINVISIGOTHx]

0:43 that globe map is awesome! I love how you can see the deep crack in the Red Sea

[@Andy_Babb]

More please!

[@geeljirejahil9570]

Dawn of sapiens, your analysis of the available data is excellent. Thanks, man. Please, do a presentation on 3-2 my transitional period, covering homo habilis, early homo and au.sediba. There is some confusion there, and your superb analysis will help alot.

[@philjameson292]

Excellent presentation, and an interesting hypothesis regarding the evolution of sweating lifting the limit of brain capacity

[@qwertyuiopgarth]

Glacial change may play a significant role in preventing Erectus from going north of 45 degrees....but control of fire and the advent of clothing may have also played a role.

[@DawnofSapiens]

That's true but the need for fire and clothing is predicated on harsh weather such as glacial expansions. It's true that modern humans would be more capable of existing in such environments but climate still posed limits on our ancestors. For example, before the current interglacial Siberia was sparsely populated with H. sapiens. Also there's a reason the Arctic was inhabited beginning only about 5,500 years ago.

[@mrbaab5932]

If it was during the Ice Age, Gibraltar has a deep trench, but much further west of there the sea is less than 300 feet depth and was a land bridge between Spain and Portugal with western Morocco.

[@DawnofSapiens]

Interesting! I tried to find some information on the strait during that time period ~1.65 mya but didn't find much. I did end up reading about the Mediterranean Sea being formed when the Atlantic ocean came crashing through what is now the strait.

[@mwstacomawa1717]

Hey I loved this. I like how you overlaid various data and produce maps of the movement. And the features diagram at first stumped me then blew my mind! Finally "what the hell is going on here?" cracked me up but deftly summarized the confusion. Your voice and style were also intriguing and relatable. More please

[@anndriggers6660]

Great video! Keep up the good work.

[@angusarmstrong6526]

Nicely done, laid out the information in an interesting but clear way

[@jeffthebluesinem2280]

One point about brain size that I have never heard addressed is whether or not brain size is more closely related to overall physique. A larger brain doesn't automatically indicate higher intelligence while a larger physical size relates to more physical strength thus an advantage for survival. Somehow better brain organization led to determining better survival skills as indicated by analyzing denisovian craniums. So while physical size conferred a survival, the advantages of efficient brain organization isn't limited by physical size.

[@jeffthebluesinem2280]

@tommorrison1960 t Thanks. I've seen some of Stefan Melo's videos, but haven't caught up to that one yet. I'll check it out.

[@russellmillar7132]

It seems homo Naledi was capable of many Sapiens' behaviors with a brain the size of a chimp. Likely factors other than just size or even brain size as a proportion of overall size contribute to what we call "intelligence".

[@bill9989]

Imagine early humans evolving in Africa. Some of those early humans stayed, while some migrated out of Africa. Those who left Africa, carried all the traits of those who stayed. But then they encountered new flora, fauna, climate and topography. New latitudes and new altitudes. These differences tested their abilities to survive. Some survived, some didn't. Those who did survive did so by adaptation and knowledge growth, which were added to the evolutionary traits and talents they carried from Africa. And then they moved further and encountered more trying environments. Some survived, some didn't. Those who survived did so through adaptation and knowledge growth, which were added again to their store of traits and talents. And then some moved further and so the process continued. Meanwhile, those who never left Africa continued to survive and multiply but were never taxed and stressed continuously as their cousins who left. Those who stayed and those who left existed apart for thousands of years until relatively recently.

[@eljanrimsa5843]

lol, I can see you want to come to certain conclusion, but the arguments don't add up much. When a species leaves its original habitat and becomes invasive elsewhere, it faces less competition, not more. As tierzoo likes to say, Africa is the most competitive server. The predators, parasites and diseases there have evolved along us, and put humans under a lot of evolutionary pressure. You better have African genes and African culture to survive in Africa. We others are the losers who couldn't make it there

[@Jolene8]

I agree with most of what you have written except, that the one's who stayed weren't as taxed as the one's who left and evolved away. They were just as taxed and challenged because of major environmental and sociological fluctuations on the continent as anyone outside of it. Hence their multi layered genetic diversity. That's even before the reemergence of people's back into Africa.

[@bill9989]

@Jolene8 I'm struggling to imagine those "major environmental and sociological fluctuations." Can you elaborate?

[@Jolene8]

@@bill9989 Environmental changes, ie., cold; heat; the appearance and disappearance of food sources; the change in geological habitats due to the elements, like floods, fire, major weather fluctuations, etc ... All of these things happened on the African continent driving ancient humans to and fro and in some cases further out beyond Africa. The latter happened also with the evolution of the body, mind and technology, so major biological shifts, also.

[@bill9989]

@Jolene8 No. All of those things happened during the millenia that humans existed in Africa. And that's what formed them. And those who left were identical to those who stayed. But then those who left encountered many new things that the remainers didn't encounter. And that caused adaptation. Simply to say that the daily, yearly, annual difficulties the remainers kept experiencing were the same as the new difficulties experienced by those who left, is not correct.

[@dc8029]

Very well done. TY sir

[@mspicer3262]

Great work. I've had an interest in how we evolved for a long time. We've learned so much since I was a kid, back in the 70's. I'm not an anthropologist, but I have read quite a few papers (ANY scientist/researcher will send you a copy of their work for free if you ask them for it - don't pay publishers to access science, kids). Personally, I think H. Erectus should be considered a number of different species, we do recognize such differences in other animals. And I think some of the differences are significant enough to warrant classification as distinct species. We have to accept that our evolutionary family tree is really messy, and we may never completely figure it out, but I see no reason to muddy the waters with a very generalized species as H. Erectus being a sort of umbrella term. There were a lot of other hominins kicking around too, who overlapped one another in both time and physical range. So many at times that it's also possible that a fraction of fossils we have collected are of hybrid individuals, we just don't know it. That alone is an interesting possibility. The introduction of DNA from a different species, at any point in the individuals lineage, could easily create significant morphological differences that create an outlier. Individuals smaller than expected, differences in brain-size, mandible and tooth shape, and so on. We see how it works in modern-day humans, as well as our misguided attempts to interbreed other animals, resulting in ligers and tigons, plus also natural interbreeding as ranges increasingly overlap, like pizzly bears. They could also be how various genetic disorders had expressed in that particular species of hominin. We just don't have enough information, but they are things that can't be entirely discounted. Yet we always assume the individual was perfectly healthy up to the time they died, and represented a "pure" form of the species they have been classified as. That one individual with the smallest ever brain-size, maybe they suffered from their form of microencephaly. In which case, the individual being an adult at death would indicate their tribe/family/clan took care of them. It would make H. Erectus much more human, modern people could relate to them, they cared for the weak. Or they may gave represented a hybrid with a smaller-brained individual, and that was passed to the offspring, whose remains we look at as an outlier for a "pure" H. Erectus. Again, we don't know, and we probably can't test for it, ever. People think science is always neat and tidy, but it's not. It's usually really messy, and if you don't get a little messy doing science, you're probably it wrong. Unless you're in virology/microbiology, in which case, you're probably a little OCD about neatness.

[@donnysandley4649]

Incredible content 🎉👏🎉🎉

[@gregjones2217]

Well done

[@mogenscamre3762]

Thank You for the video! You really caught my attention

[@davidletarte214]

thank you this video is awesome

[@brucebanner2961]

Thank you and take my subscription

[@Midnighthowlervrc]

Great video

[@morganbonczek6428]

Can you provide the source for your attribution of the Happisburgh footprints as belonging to H.erectus? I have always heard of them being attributed to H. antecessor and would be interested in reading additional information on this!

[@DawnofSapiens]

You are right those footprints are now believed to belong to H. antecessor. doi.org/10.1371/journal.pone.0088329 I was trying to use H. erectus as a broad category and then break the populations down further to other possible species. In that area antecessor is thought to be the prominent species. Prior to this it was heidelbergensis but when they found some African heidelbergensis remains (the Broken Hill skull) that dated at about 300,000 years, that species was deemed too young to be our ancestor. Antecessor became a possible suspect until the proteomic work canceled that too. There's still a lot to learn.

[@squish998]

Loved it. Very well done.

[@dreamerliteraryproductions9423]

Well done! Thanks for an interesting video!

[@matthewdolan5831]

Sweet summary.

[@bassplayersayer]

Is there no possibility Erectus crossed into Spain via Gibraltar?? If they spread to islands in Indonesia then just as possible, Gibraltar.

[@Fush1234]

I still see people who are clearly looking close to these apes. Lots of them

[@vidaripollen]

Even reptiles...in plenty

[@ricksmith9177]

Awesome

[@TheMongolianMage]

Good video. Looking forward to the rest of the series

[@Midnighthowlervrc]

Become one with monkey

[@Ozymandius_corn_maze]

I'm wondering if evolving to have our neck directly below the brain is also important to unlocking the potential to evolve relatively larger brains. A larger brain requires a larger and heavier skull. With the neck at the back of the skull, as in most other tetrapods, the overall heavier head ends up putting more strain on the neck. That costs energy, and requires a stronger neck, which then requires a larger body. Eventually the quadruped ends up with more or less the same ratio of brain to body mass.

[@DawnofSapiens]

Us modern humans have a ligament on the back of our neck that helps to hold our head steady when we run. Large quadrupeds like the Rhinoceros have this same nuchal ligament except in them its often referred to as the nuchal hump because it is massive. It serves to help hold their giant heads up while walking and running. I think you are right in that more resources are required for large quadrupeds and their big heads.

[@haldanebdoyle]

Amazing work. Keep it up.

[@adriansummers3462]

Perhaps Neanderthals had a huge thermo-regulating snout and they were covered in fur.

[@gaylecheung3087]

Doing this. How about the ones that decided to stay in Africa and evolve within Africa what classification would that be? Please answer at your convenience.

[@DawnofSapiens]

Homo ergaster would have been the original early "Homo erectus" in Africa. Homo heidelbergensis was originally thought of as the ancestor of Neanderthals, Denisovans, and H. sapiens but now anthropologists seem unsure. Mostly because the Broken Hill Skull in Zambia, Africa was discovered. This skull was dated to about 300,000 years ago and is assigned to Homo heidelbergensis, and sometimes Homo rhodesiensis. Either way, if you are a lumper H. ergaster would be early Homo erectus and Homo heidelbergensis/rhodesiensis could be considered late Homo erectus. The different species or proposed species names makes it confusing real fast.

[@bobaldo2339]

The increase in brain size trend over time hints that increased brain size is usually a positive adaptation. Yet the technology that our large brains thought up has brought on the 6th great extinction, and rapid climate change. It could be argued that the species has evolved too much of a good thing.

[@DawnofSapiens]

It's very likely that it is a positive adaptation. But it's interesting to think about the fact many of these populations lived in very different environments and brain trajectory remained the same (with the obvious exceptions of species such as naledi, floresiensis, and luzonensis). This could very well be driven by diet (protein), cooking, or some other common variable. The thing is, existing phenotype doesn't necessarily mean it's a result of positive selection. Neutral selection can result in a high frequency by chance. Hell, genetic drift can even drive a maladaptive trait to fixation across a population. On the other hand even positively selected traits can cause secondary effects which may or may not lift an evolutionary constraint. In dinosaurs feathers evolved as a thermoregulatory adaptation, but without them (and other evolved phenotypes) flying would have never emerged.

[@bobaldo2339]

@@DawnofSapiens Thanks for your informative reply!

[@rainbowcrash6990]

Comment for the algo ❤

[@jonathanturek5846]

I'm a big Harry meat head

[@travhammer]

Philosophical debate has no place in Science. I understand the issue, yet thoughts, and reflection are not fact... A common fault in the field of ( all) science... great vid.

[@DawnofSapiens]

The real problem comes when thoughts and reflections are not identified as speculation and are represented as facts. I do my best to identify when I am wondering out loud about one or another possibilities and when I am presenting scientific information by citing the research.

[@danielsee1]

You talk about brain size but what about water and fat content? How many sandwiches??

[@DawnofSapiens]

Homo sapiens are by far the fattest ape and surprisingly our bodies evolved to have the lowest water turnover than any other apes. See evolutionary anthropologist Herman Pontzer's work on water turnover today.duke.edu/2021/03/humans-evolved-be-water-saving-ape Fat provides a storage of fuel. Using less water means we can wander further from water sources more than other apes. Both of these are probably related to our independence from the trees. Homo erectus had likely at least begun evolving both of these features. To what extent? That's an interesting question. It probably wasn't as well developed in erectus but it seems highly probable that both of these were part of its migratory success (along with bipedalism of course).

[@12thpls]

​@@DawnofSapiens just read the article. Thank you! I had no idea about this.

[@adspur]

He said erectus