by Tabitha Gerry
Neanderthals are an alternate fork in the history of human evolution, what could have once had common ancestor to modern day humans took a very different path. Organisms that had comparatively larger brains, greater height and a capacity for speech were wiped out around 40,000 years ago by unknown means, though speculation ranges from climate change to competition as causes. Fast forward 40,000 years, humans are trying to understand one of their closest relatives by incorporating Neanderthal DNA into a small structure similar to the brain using stem cells.
These “mini brains” are not capable of particularly complex functions, ones that we associate with being human: thought and emotion. They are being studied to understand how different they operate functionally, which may give a clue as to why humans survived and Neanderthals didn’t. These experiments are taking place in the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and studied by the same team who commandeered the unravelling of the Neanderthal genome. Having conducted experiments on facial structure and pain threshold on mice and frogs respectively, they have now turned their attention to the brain.
The brain organoids have been created by taking the stem cells, Neanderthal DNA being incorporated in them, and using chemical triggers to form neurons which then are fused together to form clumps a few millimetres big. These are then left to develop for around nine months. As the clumps lack any sensory input about their surroundings, they vary massively in size, shape and structures that they go onto produce. Whilst these structures are massively different and don’t resemble human brains, the formation of synapses and different regions of the brain can be seen after a mere nine months.
A comparison between the human versions of these “mini brains” versus the Neanderthal version can be used to see differences between neuronal and synapse growth which could reveal key differences in neuronal structures which cause speech and organisation.
In addition to this, there is also ongoing research on the differences in brain development as a result of a person having more or less Neanderthal genes functioning in their brain.
Some scientists believe that there will one day be the means to take our knowledge on Neanderthal genes to the extreme, that we will one day be able to create a Neanderthal baby born by a human. Whilst the ethics and technology are not yet behind this venture, it may be possible that one day we could stare at species that diverged from human evolution and died 400,000 years ago.