The Mind’s Decline: How Honeybees Can Help Humans Understand Aging
The average lifespan for a man in the US is 76 years. Women tend to live about 5 years longer. Good nutrition, advanced medicine, and end-of-life care can extend our bodies’ reach into old age, but like many mammals with long life expectancies, our brains don’t always make the journey with us. In humans and captive mammals (which generally live longer than animals in the wild) the aging brain is remarkably similar, yet frustratingly mysterious.
Two things stand out:
1. Aging can impair several cognitive functions at once (memory, learning, and reaction time, to name a few).
2. Aging affects everyone differently (a group of 80 year old women can have a wide range of mental defects, and some may have none at all).
What determines whether we retain our brainpower or gradually submit to the ravages of age? Can we learn anything from other organisms, or are our brains too complicated to compare to our insect and animal counterparts?
Though invertebrates (like fruit flies and mosquitoes) have long been used to study human physiology, complex cognitive questions have generally been considered beyond their mental capabilities.
But our brains may be less complicated than we think. Last week PLoS ONE reported a study that found surprising similarities between the brains of old honeybees and the brains of elderly humans.
Do honeybees have the mental skills to qualify as models for human aging? Dr. Amdam’s lab thinks so. Honeybees are the intellectual heavyweights of the insect world: they’re navigational experts, can calculate distance from a hive (and convey the info to their hive mates), and can recognize complex visual patterns (like different human faces).
As with humans, these skills tended to fade with age. Dr. Amdam’s lab found that older honeybees had trouble forming new memories, and extinguishing (or forgetting) old ones. The ability to forget old memories is a critical part of normal human behavior; it’s the reason many elderly people can’t remember where their new home is, but have no trouble finding their old one.
So, from honeybee to human, are we all marching towards an inevitable decline? Not necessarily. Like humans, elderly honeybees fit into a broad spectrum of mental abilities. The researchers even found some old bees that “performed excellently.”
Now the question is: how do we make it into that population?
PLoS ONE article: