The day before the NASA team announced they found 7 planets around the Trappist-1 red dwarf star (three in the habitable zone)1, I went to the Duquesne University Darwin Day lecture by Dr. Nick Lane. If you want, you can watch Dr. Lane’s lecture online.
There are an amazing number of things I want to talk about from that lecture, but with the NASA announcement, I’d like to bring up one: Dr. Lane feels that bacterial-style life may be common, but multicellular life is exceedingly rare.
A quick summary goes like this: Life started on Earth 4.1-3.8 billion years ago. The big argument is whether life bothered to wait for the Late Heavy Bombardment (LHB) to end. The constant bombardment of space rubble doesn’t sound like the best time to start life, but there’s good evidence2 it either started before the LHB end or incredibly shortly thereafter.
A lot of interesting biochemistry went on in cells for the next 2.3 billion years, but it was all single-cell, with maybe a few mats or poorly separated colonies of single cells cooperating–but hardly differentiating into specialized tasks.
Then, something different happened. Multicellular life went hog-wild and became a dominant force. What happened?
According to the endosymbiosis theory of Dr. Dr. Lynn Margulis in 1967, an archaeal cell somehow grabbed a bacteria and didn’t destroy it. The two became symbiotic, and the bacteria became the powerhouse for the new cell–a primitive eukaryote. With this division of labor, the new cell took off, evolved, and became multicellular life.3
It took 2.3 billion years. It only happened once. Dr. Lane thinks that, while the odds are good we will find life somewhere–Mars or Europa or Titan4, or Trappist-1e–it will probably be bacterial or algal.
The step to mitochondria was too hard. It might be “The Great Barrier” that explains why the universe isn’t over-run by aliens. And once the step occurred, it might have been a long, difficult fight to survive it. Mitochondria lost most of their DNA to the cell nucleus, but not all. Reaching that balance must have been incredibly difficult. And mitochondria are dangerous. They’re very tiny, but the energy they produce is tremendous on a cellular scale. They keep those few genes to themselves to keep something “bad” from happening. When cells are programmed to die, the mitochondria are chief players in the destruction. And mitochondria leak out their free radicals, damaging the cell and causing aging. Mitochondria are playing with fire–or at least oxidation!
Dr. Lane may be right. He knows far more than I do. But I’d argue it might not be that bad.
First, life had to invent a lot of biochemistry. Most of the interesting biochemistry in humans and other eukaryotes can be found in yeast. The “last common ancestor” that grabbed a bacteria to become a eukaryote was extremely sophisticated biochemically. There may have been many steps necessary before a cell could even successfully grab the free-living precursor of mitochondria.
Second, a lot of bad things happened during that time. The creation of photosynthesis sucked the carbon dioxide out of the air, causing the Earth to freeze over. There’s a lot of debate as to how many times life was nearly killed off and earth became “Snowball Earth,” but it was at least once and probably a lot more. Any early eukaryotic-like cells with symbiont bacterial energy sources may have died off during those Snowball Earth periods. Survival may have favored the less energetic bacteria and archaeons.
Third, once the primitive eukaryotes got past the “let’s learn to cooperate with this thing I just swallowed” stage, they may have been very difficult to compete against. Mitochondria provide great efficiency and power. Bacteria can still survive as bacteria–and by preying on eukaryotes, but something trying to bridge the gap between them might be in a very precarious position, especially during the time when it’s learning to deal with the engulfed bacteria.
Fourth, it did happen more than once. Some bacterial cell grabbed a cell of algae and, in a process remarkably similar to what happened with the mitochondria, turned it into a chloroplast. So there were two cell lines–those with mitochondria and those with chloroplasts. Yet today, we see plants with chloroplasts and mitochondria. It turns out that mitochondria-containing cells and chloroplast-containing cells merged several times. This process is similar to the one that created chloroplasts and mitochondria. And finally, someone found a bacteria that has engulfed another bacteria. It’s a crude symbiosis, and may have happened “recently,” where “recent” is defined in something between biologically “recent” and geologically “recent.”
Dr. Lane is probably right. Multicellular life is difficult.
But it may not be hopeless.
If Dr. Lane is right, then the “Great Barrier” is behind us. If I’m right, then perhaps there are multiple Great Barriers instead of just one. Examples of these barriers might be, developing intelligence, developing technology, surviving technology, and becoming starfaring.
With the Doomsday Clock two and a half minutes to midnight, it might be more comforting to think the Great Barrier is behind us and statistically, we will survive the coming years.
1.5 billion years ago: Mitochondria
Dr. Lynn Margulis
- https://www.nasa.gov/press-release/nasa-telescope-reveals-largest-batch-of-earth-size-habitable-zone-planets-around [↩]
- http://www.livescience.com/5426-life-survived-earth-early-bombardment.html [↩]
- There’s no way I can footnote this, except to point to the link with Dr. Lane’s lecture or suggest you get his books, which are written for the general public. I’d suggest Power, Sex, Suicide as a good beginning, although you might want to read it on a Kindle or make a book cover if you are reading it on the bus. [↩]
- OK, life on Titan might be weird. Lane, in the lecture, put the odds of something biochemically similar to Earth-life at 995/1000. Titan just might be different, if life exists there [↩]
I’m not entering a 12-Step program for science denial, but I feel that way.
I’m a “facts” person. My natural inclination to go with the data is so strong, I don’t understand when others don’t. “If I give them the facts, they’ll agree with me” is so…logical.
Shortly after I decided to bring the UnSpace blog back, I wrote a post on Facebook with a series of statements. One respondent commented that there were no “facts” anywhere to back up what I said. I posted a point-by-point rebuttal. In researching the rebuttal, I avoided Snopes and tried to use conservative sources like Fox News and the Daily Mail1. I also included video whenever possible. The “respondent” replied that they didn’t believe any news sources and that they had their own special personal sources of information on Benghazi and what the Russians are doing and many, many other “special” things.
Well, that person got blocked pretty quickly. What would the point of further discussion be? I wish I’d gotten a screen capture, but I blocked them too quickly. Oh well.
The irony of the interaction struck me, though. Psychologists have known for years that facts alone won’t change peoples’ minds. If someone’s identity and world view contradicts the facts, more facts will harden their beliefs. Simple fact dumps don’t work.
I know that. If asked, I will tell you all about it. But when someone questions something, I dump facts. I’ll even pull out the math, which probably shuts down people who agree with me. My brain doesn’t “get” the idea that facts might make things worse. How could facts make things work? I love facts! I absorb them like a sponge! I’d sing Data’s “Lifeforms” song right now if “facts” weren’t only one syllable. I know fact dumps don’t work, but my actions deny the facts.
A couple years ago, I tried to take a class called “Making Sense of Climate Denial.” It was a free online class and…I just didn’t get it. I read the words, but the way my brain works, I…I couldn’t connect. I’m not sure I really understood. I gave up. I gave up pretty quickly.
If I’m going to restart this blog, I need to understand that facts alone are not enough. If someone is in denial, I need to approach them in a way that makes things better…not worse. I need to accept the facts aren’t everything.
So I signed up for the 7 week course again and, to make sure I stuck with it, I paid $49 to take the class for a certificate of completion. If I don’t complete the class with at least a 70%, I wasted the $49. It’s surprisingly strong motivation for me.
I suspect the class will generate blog posts, so there’s that. Or…maybe I just dump my homework into blog posts. Either way, it’s going to be interesting.
- Shudder [↩]
Biologists think of swamps (and other wetlands) as wonderful places.1
Swamps control runoff from rain. Here in Pittsburgh, we’re actually working at constructing artificial swamps and wetlands. These swamplets will be far cheaper than the non-biological catch basins that were proposed. In a town focusing on tourism related to our riverlife, eliminating sewage discharge is a must.
Swamps purify water. The plants and microorganisms break down toxins, collect silt, and remove heavy metals from the water. Swamps purify water better than modern water treatment plants–and often cheaper as well.
Swamps protect against hurricanes. Besides acting as a buffer zone between human habitation and the ocean, swamps and other wetlands tend to rapidly suck energy out of hurricanes. Much of the increased hurricane damage costs is attributable to wetland destruction.
Swamps have great biodiversity. That means the environment people depend on for their survival is made stronger. Biodiversity means the web of interactions between organisms are complex–a great place to go “bioprospecting.” Very often, nature has already solved chemistry and biology questions of use to humans. Antibiotics and many drugs are modified versions of biological compounds. Enzymes catalyze reactions, requiring less energy and produce purer products. Swamps and wetlands hold new antibiotics and chemical pathways that, if we don’t kill them off, we might find and make money off of!
“Draining the swamp” is such a strange metaphor. If someone says that they are “draining the swamp,” they are actually saying they’re going to make the problems worse, make solutions harder, and endanger society.
I would be suspicious of that person. Maybe they just don’t know much about swamps.
Or maybe they do, and they’re hoping you don’t.
The National Aviary in Pittsburgh brought the African penguins in from their outdoor exhibit because the weather is too cold.
Normally, that would make me laugh.
But I looked up where African penguins live. They’re from around the part of Africa closest to Antarctica. The weather gets as bad—or even worse—than Pittsburgh.
In the wild, the penguins would ride out that cold. A few, mostly the weak and sick, might die. As Steve Irwin used to say, “That’s nature’s way.”
But at the beginning of the 19th century, nature had about 4 million African penguins. Since then, the numbers have been plunging. There are only 55,000 African penguins left in the wild. At the rate it’s going, there won’t be any African penguins living free in 15 years.
The National Aviary wants to take special care of their African penguins, not only because they want to do their best for the animals, but because zoos are the last realistic hope for their species.
Careful records are kept on the family history of the penguins. They do this to maximize the genetic diversity of the species. Some of the birds are over-represented in the world captive population and aren’t permitted to breed. They are traded between zoos to ensure genetic diversity.
And they’re brought in when it’s too cold.
Because of habitat loss and pollution and even global warming, it’s unlikely that the African penguins will ever be reintroduced if they go extinct in the wild. Reclaiming habitat from industry and beach houses and toxic spills is rare. There’s only so much money for reintroduction, and there are species that might be better to spend that limited money on.
The only examples of these beautiful African penguins will be in zoos. And we’ll bring them inside when it gets too cold, because we don’t dare lose one of these remaining few.
I’m creating some graphics for Part 2 of the series on “The Problems with Computer Models.” If I’d thought things through, I would have written the series and begun publishing them, but I didn’t. I’d forgotten about the delays that artwork and research can create in multi-part series. I am working on it as well as working on the interface for the UnSpace website. In the meantime, I’ve been posting articles that I hope are still interesting.
I might need to invest in some graphing software. Creating graphs in the Adobe Publishing Suite is possible but awkward. Maybe I should put up a tip jar…