Describe two other mechanisms for evolution in addition to natural selection

early human migrations are the earliest migrations and expansions of archaic and modern humans across continents and are believed to have begun approximately 2 million years ago with the out of africa migration of homo erectus. this initial migration was followed by other archaic humans including h. heidelbergensis, which lived around 500,000 years ago and was the likely ancestor of both denisovans and neanderthals. early hominids were said to have "crossed land bridges that were eventually covered in water" .

within africa, homo sapiens dispersed around the time of its speciation, roughly 300,000 years ago.the "recent african origin" paradigm suggests that the anatomically modern humans outside of africa descend from a population of homo sapiens migrating from east africa roughly 70,000 years ago and spreading along the southern coast of asia and to oceania before 50,000 years ago. modern humans spread across europe about 40,000 years ago.

the migrating modern human populations are known to have interbred with local varieties of archaic humans, so that contemporary human populations are descended in small part (below 10% contribution) from regional varieties of archaic humans.

after the last glacial maximum, north eurasian populations migrated to the americas about 20,000 years ago. northern eurasia was peopled after 12,000 years ago, in the beginning holocene. arctic canada and greenland were reached by the paleo-eskimo expansion around 4,000 years ago. finally, polynesia was peopled after 2,000 years ago, by the austronesian expansion.

before we work more on piecing ideas together to form summaries and paragraphs, we need to look at fundamental sentence construction. imagine you are reading a book for school. you need to find important details that you can use for an assignment. however, when you begin to read, you notice that the book has very little punctuation. the sentences fail to form complete paragraphs and instead form one block of text without clear organization. most likely, this book would frustrate and confuse you. without clear and concise sentences, it is difficult to find the information you need.

for both students and professionals, clear communication is important. whether you are typing an email or writing a report or essay, it is your responsibility as the writer to present your thoughts and ideas clearly and precisely. writing in complete sentences is one way to ensure that you communicate well. this section covers how to recognize and write basic sentence structures and how to avoid some common writing errors.