The animal that makes its own food by photosynthesis
How eating mollusks saved humans from extinction. Also, what if we could make vitamin C inside our own bodies?
“All flesh is grass.”
— David Beerling
All of us should know by now that plants, algae, and few other microorganisms can fuel themselves with sunlight using a process called photosynthesis. In algae and plants, the process of photosynthesis occurs inside structures inside cells known as chloroplasts.
When we think of plants and animals, that is one of the fundamental differences that come to mind. Plants make their own “food” from light. And our own energy ultimately comes from plants.
But what if I were to tell you that there were animals that could temporarily power themselves using photosynthesis, the same processes green plants use? You might scoff at me. But it is true.
There is a kind of sea slug that can use chloroplasts that it steals from algae that it consumes. Inside the gut of the slug, these animals can then convert sunlight into energy for several weeks. These stolen chloroplasts are known as kleptoplasts, and they can be used to produce sugars and fatty acids which are then used by the sea slugs.
The process of photosynthesis can be very damaging to cells and tissues. Scientists recently found out these slugs have adapted to a solar life by converting light energy to less harmful heat, and shielding and neutralizing harmful reactive chemicals created during photosynthesis. Overall, these reduce how efficiently chloroplasts can capture light inside slugs (compared to in algae) but they allow a form of coexistence that was earlier thought to be impossible.
Which brings me to an interesting point. If certain animals can steal chloroplasts from algae, then we can also imagine that the first chloroplasts were also captured in a similar way by the ancestors of plants long ago. The first chloroplasts were probably free-living bacteria that were stolen and domesticated by other cells for their ability to harness the energy of the sun.
What if humans could make vitamin C inside our own bodies?
It's not a far-fetched idea. Most vertebrates (including some primates) can make their own vitamin C. Our ancestors lost the ability when a gene involved in the process became functionally "dead".
Our diets typically contain enough vitamin C- citrus fruits are delicious- that we don't take reviving the gene needed for making vitamin C seriously. But it raises a bigger question. With genome editing now possible in humans, we can fix some defective genes that cause diseases.
A few weeks ago, in an earlier newsletter, I shared the story of how genome editing now likely cures β-thalassemia and sickle cell disease. This is one of the greatest, unheralded stories of 2020. So far the process is promising, but punishing and expensive. Doctors remove stem cells from bone marrow and edit a gene in cells. The patients then undergo chemotherapy to destroy most of their bone marrow. Billions of gene-edited cells are infused into patients' bodies.
But what about editing the genome in so that the change passed on in humans. Should we do it? I've been following the experts for years, and I agree with the consensus right now. Right now the answer is "no". We do not know enough about the effects of making gene changes for complex diseases.
Most diseases are also not monogenic like sickle cell disease and β-thalassemia: in other words, there isn't a clear correlation between one gene and its effects. Most diseases are much more complicated than that, involving multiple genes and environmental factors.
How eating mollusks saved humans from extinction
As climate change intensifies clams, oysters, and snails might serve as a source of animal protein. Looking into this I discovered incredibly that mollusks might be responsible for the survival of our species during a prior climate change event when humanity nearly died out.
Sometime between 195,000 and 123,000 years ago, Homo sapiens populations plummeted, thanks to cold, dry climate conditions that left much of Africa uninhabitable. Everyone alive today is descended from people from a single region who survived this catastrophe.
My book is getting good reviews: thank you!
The COVID-19 pandemic was first declared by the World Health Organization a year ago, on March 11. It has been a tumultuous year, but with more people getting vaccinated each day, I remain hopeful that the pandemic will end soon. The biggest threat right now is, of course, the emergence of more infectious variants.
I want to thank everyone who encouraged me to write COVID-19: Separating Fact from Fiction. And everyone who has shared their feedback since it’s publication a few weeks ago. If you’ve not purchased the book yet, you can do so from Amazon in India here, and elsewhere here.
I am thrilled with the reviews that the book has received so far.
Sukumar Ranganathan wrote a glowing review in Hindustan Times on Sunday. I want to share one paragraph in particular that encapsulates my writing style (both here in this newsletter and in the book).
Mahapatra’s writing complements this clear-minded approach. It is crisp to the fault of being brief, and he is punctilious about distinguishing between facts and theories. This is a book where the author tells the reader what he knows, and, importantly, what he doesn’t. The names of the chapters themselves reflect Mahapatra’s economy with words: each is a single word (Origins, says one; Immunity, says another; Aftermath, says a third).
The STEM Times had this to say about the book in their review:
A short and delightful read, this book goes over the background of viral diseases and epidemics this world has already seen and how they compare to COVID-19. In his words “a pandemic is an elephant described by nearly eight billion blind people, each grasping at one or a few parts and trying to make sense of the whole.”
If the book resonates with you emotionally and you come away feeling you’ve been able to make a little bit more sense of what’s going on, it’s a success. If you like the book, please do leave me a review on Amazon or on Goodreads. That’s how people usually find new books these days.
This is my 25th newsletter. :)
I’ve been writing these newsletters without fail every week since September. And though I have interesting topics lined up, I’m mulling over taking a break. As always, I look forward to hearing from you.
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Look forward to many more of this.