Scientists have created “the largest family tree in the world”, which connects about 27 million people worldwide – living and dead.
Developed by Oxford Universitythe new genealogical network reveals how individuals around the world relate to each other in “unprecedented detail.”
Taking the form of a scientific method, research article and video, it effectively goes back in time to show where and when human populations lived.
The earliest ancestors that preceded Homo sapiens trace back in time to a geographical location that is in modern-day Sudan, probably more than a million years ago.
This image visualizes the derived human ancestors in time and space. Each line represents an ancestor-descendant link in our “supposed genealogy of modern and ancient genomes.” The line width corresponds to how many times the connection is observed and the lines are colored based on the approximate age of the predecessor
WHAT IS A GENOME?
Your genome is the instructions for creating and maintaining you. It is written in a chemical code called DNA. All living things – plants, bacteria, viruses and animals – have a genome.
Your genome is all 3.2 billion letters of your DNA. It contains about 20,000 genes.
Genes are the instructions for creating the proteins that make up our bodies, from keratin in hair and nails to the proteins in antibodies that fight infections.
Source: Genomics England
The project was published today in the magazine science by researchers at the Oxford University Institute for Big Data.
“In fact, we have built a huge family tree, a genealogy for all of humanity that models history as accurately as possible, generating all the genetic variations we find in humans today,” said study author and evolutionary geneticist Dr. Yang Wong.
“This genealogy allows us to see how each person’s genetic sequence is related to each other, at all points in the genome.
“As long as humans are at the center of this study, the method is valid for most living things; from orangutans to bacteria. This could be particularly useful in medical genetics, in separating the true associations between genetic regions and diseases from false connections stemming from our common ancestral history.
The last two decades have seen remarkable advances in human genetic research, generating genomic data on hundreds of thousands of individuals, including thousands of prehistoric humans.
This raises the possibility of tracing the origins of human genetic diversity to create a complete map of how individuals around the world relate to each other, according to the team.
Two-dimensional histograms showing the geographical location of ancestral genealogy at six time points. 1 kya is an abbreviation for a thousand years ago
THE FAMILY TREE
Because individual genomic regions are inherited from only one parent, mother or father, the origin of each point in the genome can be considered a tree.
The set of trees known as the “tree sequence” or “ancestral recombination graph” connects the genetic regions back in time with the ancestors where genetic variation first appeared.
So far, researchers have struggled to develop a way to combine genomic sequences from many different databases and to develop algorithms for processing data of this size.
However, the new method can easily combine data from multiple sources and scale to accommodate millions of genomic sequences.
The study integrates data on modern and ancient human genomes from eight different databases and includes a total of 3,609 individual genomic sequences from 215 populations.
Ancient genomes include samples found worldwide from 1,000 to over 100,000 years old.
“Essentially, we’re reconstructing the genomes of our ancestors and using them to form an extensive network of relationships,” said lead author Dr. Anthony Wilder Wons, now a doctoral student at the Broad Institute at MIT and Harvard.
“Then we can judge when and where these ancestors lived. The strength of our approach is that it makes very few assumptions about basic data and can include both modern and ancient DNA samples.
About 2,000 years ago, humans were widespread throughout the world, with the exception of much of North America, Oceania, and elsewhere.
But more than 300,000 years ago, people were more centered in Africa, the animation shows
Algorithms predict where common ancestors should be present in evolutionary trees to explain patterns of genetic variation. The resulting network contains almost 27 million ancestors.
After adding data on the location of these sample genomes, the authors used the network to estimate where the predicted common ancestors lived.
The results successfully reconstruct key events in human evolutionary history, including migration from Africa.
The earliest ancestors identified by the team are “very likely” Homo erectus, an extinct archaic human species that traces back in time to a geographical location in modern-day Sudan.
Dr Yang Wong and Dr Wohns said in a joint statement: “These ancestors lived to be more than a million years old – much older than current estimates of the age of modern humans (about 250,000 to 300,000 years ago). years) – so little of our genome is inherited from individuals we would not recognize as modern humans, but who most likely lived in Northeast Africa.
“It is very likely that these very old ancestors were homo erectus, but we cannot be sure of their identity or location without extremely ancient DNA.
“One important conclusion from our work is that the very people we often call the ‘cradle of humanity’ had ancestors back in time whose descendants are among us today.”
WHAT DO WE KNOW ABOUT HUMANITY’S JOURNEY OUTSIDE AFRICA?
The traditional view
The traditional “Out of Africa” model suggests that modern humans evolved in Africa and then left with a single wave about 60,000 years ago.
The model often claims that after modern humans left the continent, there was a short period of interbreeding with Neanderthals.
This explains why people with European and Asian heritage still have ancient human DNA today.
There are many theories about what led to the fall of the Neanderthals.
Experts suggest that the early humans may have brought with them tropical diseases from Africa that destroyed their ape-like cousins.
Others say falling temperatures due to climate change have wiped out Neanderthals.
The prevailing theory is that the early humans killed Neanderthals through competition for food and habitat.
How history is changing in the light of new research
Recent discoveries show that the “non-African” theory does not tell the whole story of our ancestors.
Instead, many smaller movements of people from Africa, beginning 120,000 years ago, were followed by great migration 60,000 years ago.
Most of our DNA consists of this last group, but earlier migrations, also known as “scattering”, are still obvious.
This explains the latest studies of early human remains found in the far reaches of Asia, dating back more than 60,000 years.
For example, remains of H. sapiens have been found in many places in southern and central China, dating back between 70,000 and 120,000 years ago.
Other recent finds show that modern humans reached Southeast Asia and Australia 60,000 years ago.
Based on these studies, people could not have come with a single wave from Africa at the time, studies have found.
Instead, the origins of man suggest that modern humans have evolved in many regions of the world.
The theory is that groups of prehistoric ancestors came from Africa and spread to parts of Europe and the Middle East.
Hence the species has evolved into modern humans in several places simultaneously.
The argument comes from a new analysis of a 260,000-year-old skull found in Dali County in China’s Shanxi Province.
The skull suggests that early humans migrated to Asia, where they developed modern human traits and then moved back to Africa.