Scientists from the Planck Institute of Molecular Cell Biology and Genetics from Germany and the Central Institute for Experimental Animals in Japan had the unique idea of injecting human genes into marmoset fetuses (monkey species from the genera Callithrix, Cebuella, Callibella and Mico) for making the brains of the animals more productive. More precisely, the scientists injected a gene called ARHGAP11B, responsible for directing stem cells in the human brain.
The scientists were amazed when seeing that the monkeys’ brains became larger and similar to the human brains. The marmosets even developed more advanced neocortexes. This is a huge step in science, considering that we’re talking about the area of the brain responsible for language and cognition.
100 days into gestation were enough
The German and Japanese researchers had been witnessing the modified brains becoming two times bigger at about 100 days into gestation.
The author of the study, mister Michael Heide, declared:
“We found indeed that the neocortex of the common marmoset brain was enlarged and the brain surface folded,”
In the end, the scientists chose to abort the monkey fetuses just in case of unforeseeable consequences.
All four genera of marmosets are part of the biological family known as Callitrichidae. The term marmoset is also used in reference to Callimico goeldii, which is Goeldi’s marmoset. Most marmosets measure only 20 centimetres long. Relative to other monkeys, these creatures show features like claws rather than nails and tactile hair on the wrists.
Marmosets are also known to exhibit germline chimerism that is not known to emerge in nature in any primates other than callitrichids. 95% of marmoset fraternal twins can trade blood through chorionic fusions, which makes them hematopoietic chimeras.
The new study was published in the journal Science here: https://science.sciencemag.org/content/369/6503/546