chrisdellavedova.com

This week in Science Tuesday we’ll focus on research with implications on the beginnings and the ends of human life. First, a study from Yale looking at the morality of infants and second, a paper from the Howard Hughes Medical Institute in Seattle suggesting that a certain class of anti-depressant can increase the lifespan of nematodes.

There have been a number of experiments examining how infants evaluate and interact with their surroundings. Most of these have proven infants to be a shallow lot – they seem to prefer “attractive” people of the same race. This week in Nature a group of Yale psychologists, led by Karen Wynn, present research that suggests that there is a bit more to our bouncing babies – they seems to assess people on their behavior as well as their looks. They designed tests to explore infants capacity to evaluate other people based on behavior. Basically, the scientists exposed six and ten month old infants to scenarios in which a character repeatedly attempts to climb a hill (the climber) and encounters either a character which either helps (helper) or interferes with (hinderer) its progress (check the Yale Infant Labs site for short videos of the scenarios). They use two tests to gauge the babies’ responses – a “reaching” test which measures preferences and a “looking time” test which assesses surprise.

The results are not surprising if you believe that humans are innately good – babies of either age almost always choose the helper after being shown the scenarios when given a choice to reach for the helper or hinderer. This results shows that infants can make decisions based on the actions of characters. In a second test, the infants were shown scenarios in which the climber subsequently approached either the helper or hinderer. Older children were surprised when the climber approached the hinderer whereas younger infants demonstrated no difference. This suggests that an ability to make personal choices based on others’ actions is established early in infant development but that the capacity to make judgements on others’ actions takes a little more time.

These experiments imply that infants may make choices about people not just based on their looks, but on behavior. These simple decisions may be evidence of the beginnings of morality in human infants. The researchers propose that this early development the capacity for moral thoughts and actions is a biological adaptation in humans.

————–

Far from the realm of infant social evaluation is research into longevity. One of the model genetic organisms for research into aging is the roundworm Caenorhabditis elegans. Like all good model organisms, C. elegans has a fully sequenced genome, is amenable to transgenic research and is easily maintained in laboratory conditions. C. elegans is particularly useful for research in aging because the fate of every cell in the worm’s body is known. A second paper in this week’s Nature out of of Nobel Laureate Linda Buck’s lab at the Howard Hughes Medical Institute in Seattle links lifespan extension in C. elegans with a drug used as an antidepressant in humans.

This is an elegantly designed study and huge in scope – the researchers tested 88,000 chemicals for their ability to extend the worms lifespan. They found over 100 compounds that extended lifespan to some degree and 13 that extended it by 30 – 60%. One of those is related to mirtazapine, which is used as an anti-depressant and sold under the brand name Remeron in the U.S. and Europe, Zispin in the UK and Ireland and Avanza in Australia. Mirtazapine is thought to act in humans by blocking signaling by the neurotransmitter serotonin. A second similar drug, cyproheptadine (trade name Periactin) is used as an antihistamine. The drugs provide the most increase in lifespan when given at a low dose in only the adult stage of development, which indicates that there is a specific window of opportunity for benefits to be gained. To establish how the mirtazapine-like compounds were extending lifespan in worms, the Howard Hughes researchers treated animals that were deficient in different aspects of serotonin signaling. Through this genetic analysis they show that the drug blocks perception of serotonin and octopamine, a second neurotransmitter. These two neurotransmitters signal the presence of food to the worms. It is possible that the drug is tricking the animals into thinking they are starving which could activate other genetic pathways leading to lifespan extension.

But tarry a bit before you dash out to your doctor’s for a Remeron prescription. While C. elegans is an excellent model system for aging research, you may have noticed there are a few differences between yourself and a microscopic nematode. There is a bit more to do before declaring mirtazapine the fountain of youth. Similar experiments would need to be done in some mammalian system – probably mouse – to see if a similar effect is seen and also what may be the negative effects of a longer life. It would be interesting to examine biochemical indicators of aging in subjects that took part in clinical trials for mirtazapine. That may provide some data to assess whether the drug has a similar effect in humans as it does in C. elegans. Scientists are still a long way from the pharmaceutical fountain of youth.

That being said, Organon (the company that developed Remeron) may not be a bad investment gamble.

Image Credits:

Yep, that’s Zach making a moral decision.

Helper/hinderer scenarios

C. elegans

The Fountain of Youth