Frogs are disappearing from the Sierra Nevada in California, from the Monteverde Cloud Forest Reserve in northern Costa Rica and from Australia. In central Costa Rica, the population of several endemic frogs has crashed. Rare and specialised species are vanishing from populated and disturbed areas and from relatively pristine places. The Costa Rican Golden Frog, the Australian Southern Day Frog and the Gastric Brooding Frog became extinct in the 1980s, among a number of others.

The extinction rate for amphibians, such as frogs, is 45,000 times higher than the evolutionary background rate. Many of these frog species were wiped out by the Chytrid fungi (Bd) that interfered with the frogs’ ability to take up critical electrolytes through their skin; this causes them to suffer a heart attack and die. The spread of this killer fungus was caused by human transportation of the African Clawed Frogs and the North American Bullfrog that are naturally infected with this fungus but not harmed by it.

What is happening to rhinoceros is typical of how we have turned on the closest and most beloved species that also call this Earth their home, namely other mammals. The five rhino species in the world today are all endangered.

There are 69 Javan rhinos left in a single population in Ujung Kulon National Park, in Indonesia. This population is so small that it is extremely vulnerable to natural disasters and disease.

There are 40 to 80 Sumatran rhinos left in the wild. Their biggest threat today is habitat loss – including forest destruction for palm oil and paper pulp – and increasingly small, fragmented populations failing to breed.

Large-scale poaching saw black rhino populations decline from around 70,000 individuals in 1970 to just 2,410 in 1995. Thanks to the persistent efforts of conservation programmes across Africa, black rhino numbers have risen since then to a current population of between 5,042 and 5,458 individuals.

Greater one-horned rhinos have made a startling comeback from the brink of extinction. By 1900, fewer than 200 individuals remained, but there are now more than 3,550 individuals due to concerted conservation efforts in both India and Nepal, their remaining strongholds.

The white rhino recovered from near extinction with numbers as low as 50 to 100 left in the wild in the early 1900s. This sub-species of rhino has now increased to around 20,375, with the vast majority living in a single country, South Africa. The northern white rhino population is now down to just two females, after the last male died in March 2018.

In pushing other species to extinction, humanity is busy sawing off the limb on which it perches

When you consider that the human population is over seven and a half billion, how can we seriously talk about survival with such pathetically small rhino populations? Let us at least be honest and admit that we have practically wiped them out.

We place armed guards to protect the last two or three individuals of a species. Can we be more stupid? The army should have been rolled out decades ago to protect the herds when these numbered in the tens of thousands if we had any conscience or common sense.

Megafauna are big animals. Elephants and rhinoceros are megafauna, as are giraffes, whales, cows, deer, tigers and even humans. The mass extinction of megafauna took place in bursts and started 40,000 years ago in Australia. The second burst was about 15,000 years ago in North and South America. The giant lemurs, pigmy hippos and elephant birds survived in Madagascar until around 1,000 years ago and the giant Moa birds in New Zealand as recently as 450 years ago.

The puzzle of why so many species of megafauna became extinct in such a relatively short period of time has now been solved. The clue lay in overlaying the chronology of these extinctions over the chronology of the migration of modern humans from our original African home. This is exactly what American geoscientist Paul Martin of the University of Arizona did in his 1973 research paper on ‘Prehistoric Overkill’. Other theories had been presented to explain the extinctions but none that were such a perfect fit. This means that man was the killer, or in this case an ‘over-killer’, from the very beginning.

In pre-human times, if an animal was a certain size, it would not be preyed upon as it was too big to bring down. The females of megafauna would normally have long gestation periods and would then have just one offspring.

There is a correlation between size and the frequency of pregnancy, and the number of offspring delivered. The bigger the size, the longer the pregnancy and the fewer the deliveries or eggs hatched.

This worked well for the megafauna until humans arrived on the scene and changed the rules they had evolved by. Humans found ways to hunt megafauna successfully and the latter could not reproduce fast enough.

It may be comforting to imagine that there may have been a time when man lived in harmony with nature, but there is nothing to support this hypothesis. In fact, it is quite the opposite.

Another victim of human migration out of Africa was the Neanderthal. Neanderthals are an extinct species of archaic human who lived in Eurasia from circa 400,000 to 40,000 years ago. Evidence shows that wherever modern humans made their appearance, the Neanderthals eventually disappeared.

There is a twist to this story. Modern humans killed and drove the Neanderthals to extinction but, before doing that, they procreated with them and, as a result of this, all non-African people are up to four per cent Neanderthal. In 2004, a new species of archaic human was discovered that was named Hobbits and, in 2010, yet another one that was named Denisovans.

There is mounting DNA evidence to show that these sibling species were also wiped out by modern human migrations, but not before having interbred with them too. No doubt, more species of archaic humans will be discovered who have met the same faith.

Scientists speculate that the modern humans that migrated out of Africa may have evolved an ‘insanity gene’ that spurred them to act without care for consequences and which encouraged them to destroy all that stood in their path. It is thought that this gene was highly successful in its survival strategy as the more ruthless humans would have an advantage and therefore would be in better position to survive and reproduce. This guaranteed this gene’s transmission to our times. Identifying this ‘madness’ gene is now an active area of scientific research.

Extinction occurs when the world changes faster than species can adapt, causing many to disappear. Modern humans change what they come in contact with; this has been our nature so far.

There are some sobering considerations to be made. Having decimated other species and degraded the ecosystems that support our own life, we seriously run the risk of becoming the victim of our own design. Stanford University Ecologist Paul Ehrlich aptly predicted that “in pushing other species to extinction, humanity is busy sawing off the limb on which it perches”.

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