Vince
Super Moderator
In a new study, published July 9, 2022 in Molecular Biology and Evolution, they focus on one of these mutated genes and attempt to trace its evolution — when and why it appeared in the human genome.
The findings suggest selective pressure from infectious pathogens like gonorrhea may have promoted the emergence of this gene variant in Homo sapiens, and inadvertently supported the existence of grandparents in human society.
The biology of most animal species is optimized for reproduction, often at the expense of future health and longer lifespans. In fact, humans are one of the only species known to live well past menopause.
According to the “grandmother hypothesis,” this is because older women provide important support in raising human infants and children, who require more care than the young of other species. Scientists are now trying to understand what features of human biology make this longer-term health possible.
When researchers previously compared human and chimpanzee genomes, they found that humans have a unique version of the gene for CD33, a receptor expressed in immune cells. The standard CD33 receptor binds to a type of sugar called sialic acid that all human cells are coated with. When the immune cell senses the sialic acid via CD33, it recognizes the other cell as part of the body and does not attack it, preventing an autoimmune response.
The CD33 receptor is also expressed in brain immune cells called microglia, where it helps control neuroinflammation. However, microglia also have an important role in clearing away damaged brain cells and amyloid plaques associated with Alzheimer’s disease. By binding to the sialic acids on these cells and plaques, regular CD33 receptors actually suppress this important microglial function and increase the risk of dementia.
neurosciencenews.com
The findings suggest selective pressure from infectious pathogens like gonorrhea may have promoted the emergence of this gene variant in Homo sapiens, and inadvertently supported the existence of grandparents in human society.
The biology of most animal species is optimized for reproduction, often at the expense of future health and longer lifespans. In fact, humans are one of the only species known to live well past menopause.
According to the “grandmother hypothesis,” this is because older women provide important support in raising human infants and children, who require more care than the young of other species. Scientists are now trying to understand what features of human biology make this longer-term health possible.
When researchers previously compared human and chimpanzee genomes, they found that humans have a unique version of the gene for CD33, a receptor expressed in immune cells. The standard CD33 receptor binds to a type of sugar called sialic acid that all human cells are coated with. When the immune cell senses the sialic acid via CD33, it recognizes the other cell as part of the body and does not attack it, preventing an autoimmune response.
The CD33 receptor is also expressed in brain immune cells called microglia, where it helps control neuroinflammation. However, microglia also have an important role in clearing away damaged brain cells and amyloid plaques associated with Alzheimer’s disease. By binding to the sialic acids on these cells and plaques, regular CD33 receptors actually suppress this important microglial function and increase the risk of dementia.
Did Gonorrhea Give Us Grandparents? - Neuroscience News
Researchers have identified a set of genetic mutations that protect against cognitive decline in older adults. A new study suggests the selective pressure from infectious pathogens like gonorrhea may have promoted the emergence of this genetic variance in Homo sapiens.
neurosciencenews.com
