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November 23rd, 2020 
Awake Goy A human gene injected into monkey brains not only made them larger, but it increased neuron function, making the animals more human.
Marmoset brains are much smaller and smoother than human brains and during evolution our brain’s neocortex “folded” to form the wrinkled appearance, allowing for a greater surface area of the neocortex in the restricted space of the human skull.
A human gene was injected into the fetuses of seven common marmosets and these genetically engineered creatures showed signs of brain expansion. Furthermore, the monkey brains formed wrinkled grooves, like what is seen in the human brain, and the number of neurons in the neocortex sharply spiked.
Parts of the brain. (Visanji, Naomi P., Patricia L. Brooks, Lili-Naz Hazrati, and Anthony E. Lang/ CC BY 2.5 )
Science Without Pop Culture, Please
The gene, called ARHGAP11B, controls conscious thinking, reasoning, and language, and after injection into the monkey brains it triggered the growth of more stem cells, which resulted in enlarged brains . According to sensationalist media, like the Daily Mail in this case, these experiments are “evocative of the recent ‘ Planet of the Apes’ films, where genetically-modified primates wage a war on humanity.” But for those of you who don’t need pop-cultural Hollywood references with your science, read on…
A new study has been published in the journal Science by lead researcher, Professor Michael Heide, from the Max Planck Institute of Molecular Cell Biology and Genetics ( MPI-CBG) working with researchers from the Central Institute for Experimental Animals ( CIEA) in Kawasaki and the Keio University in Tokyo, Japan. Japanese researcher Hideyuki Okano’s lab at the RIKEN Center for Brain Science was the first to produce transgenic marmosets with germline transmission (GT). What this means is that he pioneered the development of a technology to generate transgenic non-human primates .
Microscopy image of a section through one brain hemisphere of a 101 day- old ARHGAP11B-transgenic marmoset fetus. Cell nuclei are visualized by DAPI (white). The arrows note a new fold on the monkey’s brain. (Heide et al. / MPI-CBG)
The Big Brained Monkeys That Never Were
GT is when embryonic stem cells contribute to the reproductive cells of a mammal (germ cells) and are genetically passed to its offspring. However, in this experiment GT wasn’t required as the transgenic marmoset fetuses were not birthed. Okano said the seven marmoset fetuses were all “in utero” (inside the womb) and were taken by cesarian section for analysis at day 102 of pregnancy.
The neocortex of the common marmoset brain was observed to “enlarge, and the brain surface folded.” Furthermore, the team also noted an increased number of upper-layer neurons that increase with the evolution of primates.
This new monkey brain injection test arose from the 2015 experiment in which a single gene was inserted in the brain of a mouse that expanded the neocortex and caused the formation of many more neurons. This revealed the ARHGAP11B gene has a huge impact on brain development and increased functionality. Marta Florio at MPI-CBG told LiveScience at the time that it was “so cool” to discover that one tiny gene affects the phenotype of the stem cells and expands the neocortex.
Wildtype (normal) and ARHGAP11B-transgenic fetal (101 days) marmoset brains. Yellow lines, boundaries of cerebral cortex; white lines, developing cerebellum; arrowheads, folds. Scale bars, 1 mm. (Heide et al. / MPI-CBG)
The Bizarre Future of Gene Editing
Just like mobile phones and space travel, the entire concept of tinkering with the human genes that we pass on to our children was for a long time reserved to science fiction. But today, teams of scientists are rapidly solving the technological barriers and breakthroughs are now being made in treating illnesses from heart disease to Alzheimer’s. The same technologies being used to “edit human genes” are also being used on animals, which according to National Geographic , can be applied in the protection of endangered species like the Tasmanian devil.
Gene editing will ultimately bring back extinct animal species by mixing genes gathered from the DNA of extinct species back into existing ones. Leading the charge in all this controversial area of study is The Long Now Foundation , who boldly claim that they will “bring back the wooly mammoth .”
According to Bioethicist, R. Alta Charo of the University of Wisconsin-Madison , “De-extinction” could be applied to resurrect traits lost to commercial breeding, enabling scientists “to blend or make new species on a whim” and in our future she says billionaires might one day give their 12-year-old daughters “real unicorns” for their birthdays. Or perhaps now, intelligent marmosets that will do their homework, while they watch Planet of the Apes on a screen thinking it could never happen in real life.
Top Image: This is a marmoset. Scientists have spliced one of our genes into their monkey brains. Source: Leszek Leszczynski/ CC BY 2.0
By Ashley Cowie
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