About 1.9 million years ago, Homo erectus evolved. This human ancestor not only walked fully upright, but had much larger brains than Homo habilis: nearly twice as large, on average. Homo erectus became the first direct human ancestor to leave Africa, and the first to display evidence of using fire.
Galapagos tortoises are the product of over 3 billion years of evolution
Andy Rouse / Getty
There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms.
There are problems with each of these methods. The fossil record is like a movie with most of the frames cut out. Because it is so incomplete, it can be difficult to establish exactly when particular evolutionary changes happened.
Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. Confounding factors rack up for species that are very distantly related, making the earlier dates more uncertain.
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These difficulties mean that the dates in the timeline should be taken as approximate. As a general rule, they become more uncertain the further back along the geological timescale we look. Dates that are very uncertain are marked with a question mark.
3.8 billion years ago?
This is our current “best guess” for the beginning of life on Earth. It is distinctly possible that this date will change as more evidence comes to light. The first life may have developed in undersea alkaline vents, and was probably based on RNA rather than DNA.
Answers & Comments
Answer:
Homo Erectus
Explanation:
About 1.9 million years ago, Homo erectus evolved. This human ancestor not only walked fully upright, but had much larger brains than Homo habilis: nearly twice as large, on average. Homo erectus became the first direct human ancestor to leave Africa, and the first to display evidence of using fire.
pa follow & pa brainliest!❤ tysm.
Answer:
Galapagos tortoises are the product of over 3 billion years of evolution
Andy Rouse / Getty
There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms.
There are problems with each of these methods. The fossil record is like a movie with most of the frames cut out. Because it is so incomplete, it can be difficult to establish exactly when particular evolutionary changes happened.
Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. Confounding factors rack up for species that are very distantly related, making the earlier dates more uncertain.
Advertisement
These difficulties mean that the dates in the timeline should be taken as approximate. As a general rule, they become more uncertain the further back along the geological timescale we look. Dates that are very uncertain are marked with a question mark.
3.8 billion years ago?
This is our current “best guess” for the beginning of life on Earth. It is distinctly possible that this date will change as more evidence comes to light. The first life may have developed in undersea alkaline vents, and was probably based on RNA rather than DNA.