Life after people
Monkeypox: threat-level moderate. Magic mushrooms and depression. COVID and the brain.
This week for my Hindustan Times column, I took on a fascinating but somewhat morbid topic - life on the planet after humans become extinct. There’s no way to know what life will be like, but it is a a great thought experiment that allows us to look deep into the future. And it isn’t a depressing topic either. Life will go on.
Human extinction is inevitable (we will either go out or evolve into something else post-human), but we are also the only species that can contemplate what forms of life will exist on the planet after we are gone. Our species might be the last line of humans. Or it might evolve into something that is not quite the same as the humans of today. Yet, life will persist beyond humans.
There will be a resurgence of new forms of life; only humans will not be around to see them.
Without question, there is a mass extinction event going on now. Duke University biologist Stuart Pimm estimates that plant and animal species on the planet are dying at a rate that is one thousand times faster than new ones are evolving.
Most of the life on the planet has not been identified and perhaps will never be studied by humans. For example, we don’t even have a grasp of how many species of insects there are on the planet. As many as seven out of eight species of insects might not have been observed or named.
This is a catastrophic species loss. And climate change is making things worse.
All forms of life will be affected by the climate crisis, but not equally. Plants will thrive in parts of the planet that were once covered in ice and increases in carbon dioxide may lead to lush growth of certain plants.
There will be some animals and plants that fill in existing niches – flying birds and mammalian carnivores for example. But there will also be some animals that we cannot predict because they will be unusual.
Will humans evolve again? The biologist Stephen Jay Gould predicted that humans were a very peculiar species: If you rolled the tape of life back you would not get humans again.
If all large mammals become extinct, then smaller ones such as rodents may diversify into new species to fill ecological niches. This happened once before with the extinction of non-bird dinosaurs 66 million years ago, and it may happen again if large mammals are gone.
Rats that do not rely on humans could evolve to climb trees, take to the sky, and roam grasslands in a post-human world.
Environments that are inhospitable to us are breeding grounds for forms of life –hydrothermal vents deep in the sea, oxygen-deprived regions of the earth, subsurface ice – all of them contant myriad forms of life, many of which we will never know.
Ecologist Rob Dunn has shared his thoughts in latest book, A Natural History of the Future: What the Laws of Biology Tell Us About the Destiny of the Human Species.
Dunn mentions that evolution is all around us – even in urban environments. If some habitats are shrinking, then others are growing. Some of the most successful crop plants and animals have been selected for specific traits. And many species have opportunistically evolved with us. The biomass of cities mainly consists of humans, pets, pests, and our collective food and waste.
Humans are hosts to thousands of species. We've also selected for certain pets and agricultural plants. Some of the most successful crop plants and animals have been selected for specific traits by our ancestors. And many species have opportunistically evolved with us. The biomass of cities mainly consists of humans, pets, pests, and our collective food and waste.
Could human pets, parasites, and crop plants survive without humans? Some might (recall a few weeks ago I wrote about feral cats and dogs) but many will not be able to adapt to "wild" circumstances and die out along or after us.
Dunn writes that “if we disappear during warmer times, many species, particularly mammal species, may evolve smaller body sizes. The evolution of small-bodies mammals is well documented during the last period in which Earth was extremely hot. Tiny horses evolved.”
Life will certainly go on after humans. I’m a microbiologist so it isn’t lost on me that the predominant forms of life are microbial. They're everywhere and they're survivors. Modern humans have been around for 200,000 years. Microbes have survived for nearly 4 billion. Microbes were the first here. They'll be the last to go.
Microbes have always been the predominant form of life on the planet and there are more microbes in our bodies than there are human cells. Environments that are inhospitable to us are also breeding grounds for forms of life –hydrothermal vents deep in the sea, oxygen-deprived regions of the earth, subsurface ice – all of them harbour myriad forms of life, many of which we may never know. This should give us hope that even after human extinction, many new species will rise. Only we will not be around to see them.
Can a psychedelic found in magic mushrooms treat clinical depression?
Last week I shared some stunning news in my column.
Results of a new study published in the scientific journal Nature Medicine show that psilocybin, a powerful psychedelic compound found in “magic mushrooms” can treat patients suffering from clinical depression.
Psilocybin was more effective than a common antidepressant, escitalopram. Brain scans of patients also hinted that psilocybin works in a completely different way from known antidepressants.
People suffering from depression can face low moods together with repetitive patterns of thought. These behavioural patterns have signatures in the brain that are thought to contribute to depressive symptoms. Unfortunately, psychotherapy and antidepressant drugs don’t always alleviate symptoms for everyone suffering from depression.
New research on the use of the psychedelic compound, psilocybin, has found that just one or two doses of this drug provided in a clinical trial in conjunction with psychological support can reduce symptoms of depression even in patients who aren't responding to other forms of treatment.
Many patients who have benefitted from psilocybin say that their brains seem to have been reset like computers that have been restarted.
Functional MRI brain scans from both trials showed that there were changes in brain function that persisted beyond the use of psilocybin. This indicates that the changes are long-lasting.
What psilocybin seems to be doing is help the brain become more connected, so that it works more fluidly outside of the rigid patterns of behaviour that it has formed. These inflexible patterns are often associated with depression. People suffering from depression report facing negative thoughts and behaviours that they can’t escape. The improvements in brain connectivity correlate very well with improvements in mood and mental state.
Although more work is needed, the beauty of the study is that it shows that a very short course of psilocybin can provide a long-term benefit to patients not responding to standard treatment. What I found most stunning is that even a single dose of psilocybin can have a lasting effect on brain connectivity.
What is also intriguing about this study is that it shows both the effectiveness of the use of psilocybin in treating patients and that the mode of action might be different from approved antidepressant drugs. Psilocybin is a naturally occurring psychedelic compound that's found in around 200 different kinds of mushrooms that grow around the world. Since the late 1960s and early 1970s, psychedelic compounds such as psilocybin have been illegal in most countries.
Pharmaceutical companies have developed drugs to help people deal with anxiety, depression, and other psychiatric disorders, but they are not equally effective in treating everyone. Alternative means such as natural psychedelic compounds could help people better deal with these conditions.
Certainly, these compounds which have been used by indigenous communities recreationally and for spiritual experiences for thousands of years might serve to treat psychiatric conditions. Psilocybin is not addictive in the physiological sense and isn’t toxic at the doses administered. But because psychedelics are still illegal and not approved for any condition, they should not be consumed unless under the direct guidance of a physician as part of a clinical trial.
Future studies with psilocybin will include Phase 3 trials for use in depression to find how safe and effective it is in a larger population. Additional studies will also glean out just exactly how it works. Right now, no one really knows.
Monkeypox: threat-level moderate
Citing that human-to-human transmission is likely to be underway, the World Health Organization has indicated the following:
Currently, the overall public health risk at global level is assessed as moderate considering this is the first time that monkeypox cases and clusters are reported concurrently in widely disparate WHO geographical areas, and without known epidemiological links to non-endemic countries in West or Central Africa.
The public health risk could become high if this virus exploits the opportunity to establish itself as a human pathogen and spreads to groups at higher risk of severe disease such as young children and immunosuppressed persons; a large part of the population is vulnerable to monkeypox virus, as smallpox vaccination, which confers some cross-protection, has been discontinued since 1980 or earlier in some countries.
What I’ve watched.
How COVID affects the brain
This is something I’ve written about as well.
What I’ve read.
An editorial in Science arguing that the U.S. needs better gun control in the wake of yet another deadly shooting in a school.
Lasers have uncovered pyramids in the Amazon.
Viruses that were on hiatus during COVID are back — and behaving in unexpected ways.
Tomatoes gene-edited to include vitamin D.
Endnotes
We lost a part of our youth yesterday.
I’ve been listening to this song on loop for nearly a day now. :-(