Level 1 — Absolute Beginner
A long time ago, our ancestors were not alone. They lived near other kinds of early humans, like Neanderthals.
Scientists already knew people today carry some Neanderthal DNA. Now they found something new.
A new study says people also carry DNA from two other groups of early humans. No one has ever found bones from these two groups.
Scientists only know about them because of tiny clues hidden inside human DNA today.
- ancestor
- a family member who lived a long time before you
- Neanderthal
- an extinct type of early human that lived alongside modern humans
- DNA
- the material inside our cells that carries information about who we are
- group
- a number of people or things together
- bone
- a hard part inside the body of humans and animals
- clue
- a small piece of information that helps solve a mystery
- hidden
- not easy to see or find
- study
- careful research done to learn about something
Level 2 — Elementary
Scientists have long known that many people today carry small amounts of DNA from Neanderthals and Denisovans, two extinct relatives of modern humans who interbred with our ancestors thousands of years ago.
A new study published in the journal Science reports that people also carry DNA from two additional extinct groups that had never been identified before, neither of which has ever turned up in the fossil record.
One of these groups appears to have split from the human family tree around 800,000 years ago, close to when Neanderthals and Denisovans branched off, and its DNA now makes up about 1 percent of the genome of every person alive today.
The other group seems to have lived in Eurasia even earlier, more than 1.7 million years ago, likely around the same time as Homo erectus, though scientists have identified it only through patterns buried in modern human DNA.
- interbreed
- to have offspring together across different groups or populations
- extinct
- no longer existing; died out completely
- identify
- to recognize or establish what something is
- fossil record
- the collection of preserved remains and traces of ancient life
- split
- to divide or separate into different paths
- branch off
- to separate from a main group or line, forming a new direction
- genome
- the complete set of genetic material in an organism
- pattern
- a repeated or noticeable arrangement of something
Level 3 — Intermediate
Building on decades of research showing that Neanderthal and Denisovan DNA persists in living humans, a study published July 30 in the journal Science identifies traces of two additional, previously unknown archaic hominin lineages embedded in modern human genomes.
Crucially, neither lineage has left any confirmed physical trace in the fossil record; their existence has been inferred entirely through a new technique that scans genomes for DNA segments too divergent to have come from any known ancestral population.
One lineage appears to have diverged from the ancestors of modern humans in Africa roughly 800,000 years ago, around the same era as the Neanderthal Denisovan split, and its genetic contribution now accounts for approximately 1 percent of the genome carried by every person alive, regardless of geographic ancestry.
The second, still more ancient lineage seems to have existed in Eurasia, diverging over 1.7 million years ago and likely coexisting with Homo erectus, a finding that reinforces a growing scientific consensus that human evolution involved repeated interbreeding among numerous related hominin populations rather than a single, linear line of descent.
- archaic
- belonging to a much earlier, ancient period
- hominin
- a member of the group including modern humans and their extinct close relatives
- lineage
- a line of descent from an ancestor
- diverge
- to separate and develop in a different direction
- infer
- to reach a conclusion based on evidence and reasoning rather than direct observation
- ancestral
- relating to one's ancestors
- coexist
- to exist together at the same time or place
- consensus
- general agreement among a group of people, especially experts
Level 4 — Advanced
Extending decades of research demonstrating that Neanderthal and Denisovan DNA persists within contemporary human populations, a study published July 30 in the journal Science identifies traces of two additional, hitherto unrecognized archaic hominin lineages embedded within modern human genomes.
Crucially, neither lineage has yielded any corroborated physical trace in the fossil record; their existence has been inferred exclusively through a novel technique that scans genomes for DNA segments too divergent to be attributable to any previously documented ancestral population.
One lineage appears to have diverged from the ancestral line of modern humans in Africa approximately 800,000 years ago, roughly contemporaneous with the Neanderthal Denisovan split, and its genetic contribution now constitutes approximately 1 percent of the genome carried by every person alive, irrespective of geographic ancestry.
The second, still more ancient lineage appears to have inhabited Eurasia, diverging upward of 1.7 million years ago and plausibly coexisting with Homo erectus, a finding that reinforces a burgeoning scientific consensus that human evolution unfolded through repeated interbreeding among numerous related hominin populations rather than a single, linear trajectory of descent.
- contemporary
- existing or occurring at the present time
- hitherto
- until now; up to this point
- corroborated
- confirmed or supported by additional evidence
- attributable
- able to be explained as caused by a specific source
- contemporaneous
- existing or happening during the same period of time
- constitute
- to form or make up a particular whole
- irrespective
- regardless of; without taking something into account
- burgeoning
- growing or developing rapidly
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