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Overview
The world is changing rapidly. People are more interconnected than ever, yet some politicians complain about threats from other cultures and people who call for equality. These issues have been around since the beginning of time, but it’s important to understand our history so we can learn from it.
DNA, genetics and science can give us insight into our ancestry. History has shown that human migration is a constant process, with people moving from one place to another. Our ancestry is intertwined throughout history. This pack will teach you how we know that Madagascar was once linked to Taiwan; why ancient populations aren’t as extinct as they seem; and just how closely related we are to Neanderthals.
Big Idea #1: Scientific advances in genetics give us unique insights into early human history and development.
DNA analysis is an amazing scientific tool. It can help us understand our species and where we come from. But it’s not always easy to understand.
A good metaphor is like a grenade that explodes in a room. It’s hard to figure out where the pieces of shrapnel came from without doing DNA analysis, which is similar to gathering those bits and figuring out what they mean.
DNA is the genetic code that we inherit from our parents. It consists of molecules called nucleotides, which are made up of chemicals called adenine (A), cytosine (C), guanine (G) and thymine (T). The chains are about three billion chemical blocks long.
Genes are the building blocks of life. They contain instructions that tell us how our bodies work. Mutations occur at random in genes and make us unique individuals, as well as being a way to trace ancestry. If you compare two people’s mutations, the more differences you find between their genes, the further they are away from sharing a common ancestor.
DNA study has drastically changed the way we view evolution. Scientists used to think that different subsets of the human species evolved in parallel on different continents. For example, Europeans and Indians evolved separately from each other on their respective continents.
Scientists used to think that all humans descended from a common male ancestor. However, they have since revised their opinions based on mitochondrial DNA, which is inherited through the mother’s side of the family. Scientists now believe that there was only one female who lived about 200,000 years ago in Africa and was the original “Mitochondrial Eve.”
If the old theory about humans coming from different parts of the world was true, then any shared ancestor would be very old and part of a migration around 1.8 million years ago.
But if we see Eve as our most recent common ancestor, then modern humans must have evolved in Africa and spread across the world 50,000 years ago.
Big Idea #2: The ancestors of modern non-African humans interbred with both Neanderthals and Denisovans.
Around 50,000 years ago, the ancestors of modern humans started migrating out of Africa. They encountered other species of human beings that descended from Homo erectus (Neanderthals). Within 10,000 years they had replaced all other species.
Neanderthals were a species of humans that had distinct physical characteristics. Their large frames and projecting brows gave them a reputation for being primitive, but archeological findings show they were just as smart as our ancestors. Genome sequencing has also revealed more about their history; the author was part of an international team that sequenced the Neanderthal genome in 2007. They found that non-African humans share common mutations with Neanderthals, which suggests interbreeding occurred between 54,000 to 49,000 years ago when modern humans first left Africa but before they spread out across different continents.
