Friday, December 27, 2013

139.5 - And Another Thing #1: inheriting acquired characteristics

And Another Thing #1: inheriting acquired characteristics

To wrap up this week's show, three quick examples of another occasional feature, this one called And Another Thing, where we go into something non-political, usually some cool science stuff.

To start off, here's something interesting: It's long been held that physical characteristics - as opposed to socialization - are transferred from one generation to the next through genes. An old alternative idea commonly called Lamarckism after Jean-Baptiste Lamarck, which held that the life experiences of parents - their "acquired characteristics" - could be passed on to their offspring is known to be wrong.


It now develops that learned experiences can be transferred to offspring. Not by a different mechanism than genes, which remain the only way characteristics are transmitted, but by potentially affecting how genes are “marked” by other molecules.

Such “markings” are called epigenetic changes and they can affect which genes are turned off or on, that is, how the genes are expressed. It develops that some of these changes - not all, but some - are maintained across generations.

In a new study, researchers say they have found that specific learned information can be transmitted through epigenetic changes in sperm, at least in cases involving traumatic experiences and at least in mice.

The researchers trained mice to fear a cherry blossom-like smell and then let these mice mate and have offspring. These offspring showed more fearful responses to the cherry blossom scent than to a neutral scent despite never having encountered either of the smells before.

Moreover, they added, the next generation of offspring, the grandchildren of the original group, showed the same behavior. The researchers were able to relate the behavior to changes in brain regions used to detect the feared scent and to epigenetic marks in the sperm on the gene responsible for detecting the smell.

So, Jean-Baptiste Lamarck, you were still wrong, but not as wrong as we thought. And the more we learn about biology and evolution, the more amazing the whole process becomes.


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