Though our Grandmothers may be protective (or perhaps even territorial) over us at times, not many of us would expect them to engage in a physical fight to defend us. However, the more mature, female members of a particular termite species do even more than that…
The workers (those that forage for food and tidy and maintain the nest) of the Neocapritermes taracua species develop the self-sacrificing tactic of ‘bombing’ foreign nest-invading termites as they age, with older workers taking on a larger share of the defence. So much for retiring and indulging in your pension pot!
This explosive ability starts to develop as the worker’s food intake, and thus their survival, diminishes. As they begin to starve a specialist pair of glands develop to help the ladies with their ‘final mission’.
Residing on the termite’s back, these ‘backpack-like’ glands hold the copper-containing protein, which causes the formation of blue crystals within the glands. When bitten into by attackers, the puncturing of these backpacks causes its contents to be explosively released. Outside of the termite’s system, and as the blue colour of the crystals fades, the released substance becomes a ‘sticky trap’ for the termite’s predator. This hampers invaders and saves the nest, all thanks to Grandma!
And it’s not just these termite grandmothers that act in such an altruistic way. Evolutionarily it is believed that human grandmothers looking after their grandkids have increased human lifespan by protecting and preventing attack upon their dependent and defenceless grandchildren, whilst their mother seeks the opportunity to have more children. Meanwhile, ‘grandmothering’ behaviour is also known to increase ones lifespan, by reducing the amount of labour-intensive childcare that is bared by the mother.
To test this idea of loving Grandmas increasing our lifespan, a collaboration of mathematicians and scientists created a computerised model of the behaviour. Using chimpanzee lifespan, they discovered that grandmothering can double a lifespan in less than 60,000 years (in evolutionary terms, a much shorter phase than it seems!)
But why do our grandmothers adopt such a caring attitude? Put simply, menopause.
It’s thought that the menopause results in a ‘change of tactic’ for females. While initially females focus on producing offspring to ensure that their genes are passed on, following menopause and unable to produce babies, Grandmothers assume a position of care thought to protect their offspring.
This mechanism of protecting ones genetic line is rife within the natural kingdom and applies equally within the termite species, whereby their exploding behaviour prevents the attack of their siblings and parents who hold a proportion of Grandmother’s genes.
This natural response to protecting the family may come as a result of the evolutionary raison d’etre of ‘passing on’ one’s genes, where it becomes just as important to nurture and protect your ‘additional genetic investments’ (AKA your existing family and offspring). Much similar behaviour is believed to have evolved to ensure the survival of the all-important genetic lineage. So whilst Grandmothers may seem kind and caring, an underlying evolutionary cause could be the reason for their loving behaviour!
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