One of our genomes must be changing rapidly because we are getting sick at an alarming rate.
As we explored in “Which Genome is Running the Show”, our nuclear genome hasn’t changed much over time. In fact, humans and chimps share a surprising 98.9% of their DNA. Of course, thanks to our brain’s frontal lobes, we’re radically different (you might argue that point with some people you encounter day-to-day). So is our mitochondrial genome the one that has really experienced the most change in the last few generations?
Is Mom’s mitochondrial genome to blame?
Let’s take a Squint.
What Mom Left
At the equator, we experienced a consistent 12 hours of sun and 12 hours of darkness every day. Now that’s what I call circadian rhythm! With a {consistent light environment}, our mitochondria could stay tightly coupled and just focus on the job of basking in the UV light at the equator. The closer one lives to the equator, the less uncoupling was needed in the mitochondria because the UV sun (and perfect circadian rhythm) provided all the ingredients for self-regulated autophagy and apoptosis (that’s our cell repair and maintenance program). At the equator, a perfect balance of consistent light and dark (12 hours of light, 12 hours of dark) allowed us to thrive with our tightly-coupled, circadian-synced, mitochondria.
If you go back far enough, we are all immigrants from Africa, and our mitochondrial genome was the powerhouse that allowed us to adapt to our new surroundings as we left equatorial Africa. We couldn’t just leave the warmth and UV light of equatorial Africa and expect our bodies to perform. We had to change, to adapt to new environmental influences that our mitochondria were sensing (less light and more cold). Thankfully, our mitochondrial DNA is our “adaptable” DNA that takes on the job to manage our energy metabolism, to make us run as efficiently as possible in any new environment. Of course, this DNA comes from mom, always ready, always prepared for everything!
So what happened to our mitochondria when the light and temperature changed dramatically when early humans headed out of Africa? Mom dealt. She always does!
What Mom Found
For the haplotypes that moved north, life wasn’t all UV sunlight and delicious tropical fruit. It got cold – really cold. And our tightly-coupled mitochondria needed to loosen up, to adapt to colder environments. Our mitochondria needed to produce heat, and fast. We couldn’t just use all of our energy to hunt and gather, we needed to stay warm. So, our body made some important changes, and our mitochondria became more heat-efficient powerhouses. Northern haplotypes had to create energy-efficient heat engines to have any chance of surviving out of Africa.
Our mitochondrial DNA allowed us to adjust to our new, colder environments with less consistent light. As we migrated away from the equator, the sun wouldn’t be directly in the sky, but at an angle, meaning different rays of light reached our environment—even in the middle of summer. There was no African heat, our seasons changed, and our mitochondria had to adapt.
We had to make some serious changes to stay warm, to make the most energy-efficient mitochondrial powerhouse possible.
How Mom Got Herself Together
We still needed energy – to run from predators, to hunt, to fish, to gather food – but we also needed energy to create heat in our bodies. We had to adapt our mitochondria to be more energy-efficient – to produce energy AND heat.
These drastic changes in our physical environment meant that the skin of migrating ancestors would need to change. We needed to attract as much light as we could. So, we become paler in order to soak in more sun. We also created a new kind of fat (brown fat), which is the type of fat that creates heat when burned. We basically needed to become more efficient solar panels, able to attract light that was much weaker than before. This was another world compared to east Africa. Our mitochondria needed to use its energy to make heat, and we would need to sacrifice our energy-making ability (ATP) to prioritize heat.
So, what did our mitochondria do to adapt to a new environment? We “uncoupled” – we created a “hybrid” mitochondria of sorts – that could survive warm and cold weather.
Uncoupled Mitochondria? Is that like “Conscious Uncoupling”?
Not really. We did divorce ourselves from year-around UV light and the warmth of equatorial Africa. As part of the divorce, we had to change our uncoupling efficiency system in our mitochondria. In new non-equatorial environments, our mitochondria had to uncouple – to change, to produce more heat, to survive. All maternal haplotypes produce varying amounts of heat via this uncoupling efficiency. It’s how we learned to survive our new environment. The further one goes from the equator, the more uncoupling humans need to control their cellular health to make heat. Equatorial light is the most powerful on earth, and this is the light that human mammals evolved under, with tightly-coupled mitochondria, exposed to plenty of UV light, running with perfect efficiency.
Mom’s Always Prepared and You Can Be Too
Migrating out of Africa meant many women across the globe had to make serious adaptations to survive. These adaptations weren’t just about adding extra layers of clothing, this required changes at a cellular level. Changes needed to be made in our mitochondria, to adjust our energy management system, to make more heat to survive.
Let’s keep Squinting to better learn what we can learn from mom to best adapt our mitochondria to our own environment today.