Ants die with full health and physical ability

The analysis of biological aging in social species is important to understand the influence that group life has on the evolution of the aging of members of society. To the surprise of Boston University researchers, worker ants of the species Pheidole dentata show no signs of decline in their health or physical abilities as they age and die “at their best.”

Social insects offer excellent opportunities to test hypotheses related to the aging/behavior pairing. This is the theory of Ysabel Giraldo and James Traniello, from Boston University (USA), who are convinced that, by observing animals such as ants, we may be able to learn something about how social interactions shape the behavior and neurobiology of individuals. 🇧🇷 Concerned about human aging and some molecular mechanisms related to cell death in the brain and the appearance of neurodegenerative diseases, such as Alzheimer’s or Parkinson’s, it occurred to them to question what happens to the ants’ brains when they age.

Although, of course, human and ant brains are very different, studying the behavior of these insects may have something to do with our own social organization.

To establish possible relationships, they studied hundreds of worker ants of the species Pheidole dentata, looking for phenomena similar to those that occur in humans with age: increased cell death in certain areas of the brain, decreased levels of certain important neurotransmitters, such as dopamine and serotonin , and a decrease in performance in daily tasks.

They observed them and recorded data about their activity in their daily tasks, such as caring for larvae, the ability to follow pheromone tags to cooperatively collect food, or the removal of dead individuals. With patience, persistence and ingenuity, the researchers measured the ants’ performance over two years.

When analyzing the information obtained, Giraldo and Traniello were amazed. Surprisingly, the worker ants, which live up to 140 days in the lab, showed no signs of age-related decline before dying. Worker ants are born clumsy and then acquire behavior and expand their repertoire. So the researchers expected there to be a normal curve for insect functions: improvement, peak performance, and decline. More or less like human beings: we lose hearing, we lose sight, we lose motor coordination and also memory and, over time, we die.

But not. The ants showed no signs of aging and, in fact, some of their functions even improved with age, such as the ability to follow pheromone tags. Their brains did not show increased apoptosis, or cell death, in functionally specialized compartments or decreased synaptic density between neurons. On the other hand, serotonin and dopamine levels, contrary to expectations, increased in elderly workers. The animals maintained brain functions that support smell and motor coordination regardless of age. Also, they became more active as they got older.

The question is how this phenomenon is possible and why it happens. And of course, also, how can we humans become a little more like ants in our ability to avoid senescence? There is currently no answer. Perhaps the ants’ advanced social organization makes their brains more efficient and resilient, or perhaps other factors are at play.

Scientists are also not sure why ants “at their best” actually die, if not by accident or predation.

Source: Environmental Hygiene, Ysabel Milton Giraldo et al: Lifespan Behavior and Neural Resilience in a social insect, Proceedings of the Royal Society B, 2016

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