Human evolution is a process that started with primates and has led to Homo sapiens. Humans differ from primates in that we have evolved bipedalism, dexterity, and complex language. Primates diverged from other mammals around 85 million years ago. Then primates evolved into different clades, and two of them were hominids and gibbon families. This happened around 15 to 20 million years ago. African and Asian hominids diverged around 14 million years ago. Hominini, which also included Australopithecine (The closest biped relatives to modern humans. They are extinct, and they didn’t belong to the Homo genus.), diverged from Gorillini and Pan genus around 4 to 9 million years ago. The first Homo genus appeared around 2 million years ago, and it is called Homo habilis. Homo habilis knew how to use stone tools. Over the next million years, Homo habilis evolved into Home erectus and Home ergaster. It is believed that they were the first ones to use fire and more complex tools. They were also the first Hominini line to leave Africa. They spread all over Africa, Asia, and Europe 1.3 to 1.8 million years ago. Modern humans evolved around 300,000 years ago. Scientists think that modern humans evolved from Homo heidelbergensis, Homo rhodesiensis, or Homo antecessor and migrated out of Africa around 50,000 to 100,000 years ago. They replaced the already existing populations of Homo erectus, Denisova hominins, Homo floresiensis, Homo luzonensis, and Homo neanderthalensis. DNA evidence suggests that modern-day humans have traces of Neanderthals and Denisovans genomes in them because of interbreeding
Homo sapiens has now spread all around the world. It is generally believed that our ancestors were from Africa. There are different theories about modern-day human origin. On of the theories says that humans evolved from local ancestors, and the other theory says that we evolved in a single region and then spread around the globe. The first one is called “multi-regional,” and it means that the evolution of Homo sapiens happened in a lot of different places over a long period of time. Different populations eventually interbreed, and this led us to the single Homo sapiens.
The second one is called “Out of Africa,” and it means that Homo sapiens evolved from a single group of ancestors. It happened around 300 000 to 200 000 years ago, and around 100 000 years ago, Homo sapiens spread to the Middle East. This theory says that modern humans replaced all other human species without any interbreeding.
Modern humans became common all around the world less than 50,000 years ago. It is thought that the differences we have nowadays in different geographical areas evolved around 60,000 years ago. It is the result of adaptations and different environments.
The latest findings still suggest that Homo sapiens originated in Africa about 60 000 years ago, and it also says that they interbred with local human species. Scientists have found in all non-African populations traces of Neanderthal and Denisovan genes.
Neanderthal and Denisovan people emerged in Eurasia. Africa and Eurasia were in isolation before Homo sapiens emerged, which means different species before H. sapiens didn’t interbreed. When Homo sapiens migrated from Africa, it absorbed and replaced all the local populations.
Some scientists suggest that other homonini species became extinct because Homo sapiens was more violent. However, it is unlikely that all of the previous species have become extinct due to violence. For example, scientists have found signs of warfare in Neanderthal skeletons. Even chimpanzees show signs of violence. Some scientists think that abstract thinking and communication are far more dangerous than weapons. Homo sapiens have the ability to cooperate, plan, strategize, manipulate, and so on. So that might be the reason why other human species became extinct. This theory is hard to prove, but archaeological records show us that after a few thousand years of Homo sapiens arrival, Neanderthals vanished. The other reason might be that Homo sapiens lived in big groups, and due to that, there was less inbreeding and the health of each individual was also better. Modern humans also have “hyper adaptability”, which means that we can adapt to almost every new situation, and if we are unable to adapt, then we change our surroundings.
Some scientists say that there are no other species at all because the definition of species says that two different species cannot have fertile children. But, like earlier said, Homo sapiens was able to breed with other Homo “species”.
Sources:
https://en.wikipedia.org/wiki/Human_evolution
https://en.wikipedia.org/wiki/Australopithecine
https://australian.museum/learn/science/human-evolution/when-and-where-did-our-species-originate/
https://www.yourgenome.org/stories/evolution-of-modern-humans/
https://www.sciencealert.com/did-homo-sapiens-kill-off-all-the-other-humans
https://english.elpais.com/usa/2021-07-06/why-are-we-the-only-human-species-left-on-the-planet.html