Everything and everyone on this planet have been exposed to over 1,00,000 new chemicals, and that's just in recent years. Most chemicals have been identified as endocrine disruptors, but there is no safety information on over 85 per cent of them
The English naturalist, Charles Darwin, best known for his theory of evolution, doesn’t really need an introduction. In 1871, he proposed a theory on sexual selection that triggered off a debate which continues today. Darwin’s theory explored what were the ‘oomph’ factors in play when individuals were attracted to one another and competed against themselves to ‘win’ their preferred mate. He went beyond this basic idea and attempted to decipher the secret behind sex ratios as they occurred in the natural world. He believed that a 1:1 ratio was the most advantageous and natural ratio. He struggled with this theory and finally stated that ,“In no case, as far as we can see, would an inherited tendency to produce both sexes in equal numbers or to produce one sex in excess, be a direct advantage or disadvantage to certain individuals more than to others.” He went on to say that the whole sex ratio question is intricate and it would be safer to leave its solution for the future.
More than half a century later, in 1930, RA Fisher, an English biologist, came up with an evolutionary model that explained why the sex ratio of most (not all) animals is 1:1. Known as the Fisherian principle, the theory predicts that since the ‘cost’ to produce a son or daughter is the same, the population’s sex ratio should be 50:50 through a mechanism of natural selection. In 1997, biologists conducted a simple and robust experiment to test the Fisherian theory. They created separate populations of a small fly belonging to the genus Drosophila. Each set up population of the fly had a deliberate sex ratio bias. If Fisher’s principle were to really work, a natural process would have to select for the autosomal suppressors (linked directly to sex determination) and gradually restore the population to a 1:1 ratio. Over six years they monitored, counted and sexed more than 2,50,000 flies and saw the experimental populations evolve from 16 per cent of males to 32 per cent of males in 49 generations. They deduced it would take 330 generations over a time of 29 years to reach 49 per cent. It’s apparent through this experiment that a skewed ratio could take generations and many years to correct itself, even in the case of a fly.
Today a lot of research and experts believe that the male gender is in danger. A multitude of chemicals is finding its way into our water sources and are reportedly feminising males from fish to mammals, including people.
Fish are known to be an indicator species and are particularly affected by pollutants, as water sources are the first to get polluted and quite literally overtime, can become a ‘holding tank’ of whatever pollutant or chemical finds its way into it.
The chemicals released into the environment are absorbed by all animals and interfere with their endocrine system. They are nicknamed ‘gender benders’. Various studies have clearly indicated and documented the impact these chemicals are having on fish. In Britain, 50 per cent of the male fish in lowland rivers were found to be growing eggs in their testes. Contraceptive pills which pass unaltered through sewage treatment are being held partly responsible along with sewage discharge which has been found to contain demasculinising man-made chemicals. Feminising effects have now been discovered in fresh-water fish species in Japan, Africa, and in sea fish in the North Sea, the Mediterranean, Osaka Bay in Japan and Puget Sound on the US west coast.
The UK and European epidemiological studies have solid data that shows the existence of fish with gonads containing male and female tissue and its direct association with effluent discharges. The incidence and severity of this inter-sex condition is also directly related to the proportion of estrogen found in the treated sewage effluents in receiving waters.
Cane toads, an extremely resilient and prolific breeder which spread across Australia and are classified as an invasive species, have also been affected. Research at the University of Florida found that 40 per cent of the male cane toads in intensively-farmed parts of the State had become hermaphrodites. Florida male alligators have been affected as well and have been found to have very high oestrogen levels, abnormal testes, smaller penises and reproductive failures. Around the Great lakes of America, species across the board have been found to be contaminated with over 400 different chemicals and the males as a result have been found with female characteristics. Male herring gulls and peregrine falcons have been found producing the female protein required to make egg yolks. Hermaphrodite polar bears with penises and vaginas have also been discovered and the males that were seemingly unaffected had reduced sperm counts and penis lengths.
CHEMTrust, a charity, compiled a report from 250 scientific studies from around the world. The studies ranged from the Arctic to the South African plains to the oceans, covering key species that lived in all these zones. What they reported is nothing short of shocking. “Feminisation of the males of numerous vertebrate species is now a widespread occurrence. All vertebrates have similar sex hormone receptors, which have been conserved in evolution. Therefore, observations in one species may serve to highlight pollution issues of concern for other vertebrates, including humans.”
Everything and everyone on this planet have been exposed to over 1,00,000 new chemicals, and that’s just in recent years. The number is much higher if we look at the last few decades. Many of these chemicals have been identified as endocrine disruptors and gender benders but there is no safety information on over 85 per cent of them. The European Commission has admitted that 99 per cent of them are not even adequately regulated. It’s not just medicines or contraception, these chemicals are used in food wrapping, cosmetics, flame retardants in furniture and electrical goods, coolants in transformers, many pesticides and even baby powders.
Eventually all waste and things we throw out will break down and find its way to our water, and from there it will eventually find its way back to us. The natural path that evolution was taking seems to have been thrown way off course. Recently there’s also been talk of skewed sex ratios in India’s tiger populations in various States and scientists and conservationists are finding ways to achieve a more favourable balance. Could this too be a direct result of gender benders in our environmentIJ Perhaps, but either way, like the fly, for a species like the tiger to recover from a sex ratio bias, time will not be the only deciding factor for nature to fix our doing and find a way.
(The writer is a wildlife film-maker)