How old is life, really?

I've mentioned the theory of panspermia in earlier posts; briefly put, the theory that life is ubiquitous and that it evolved somewhere other than earth.

A significant component of the evidence offered to support this theory is that life seems to have appeared so early on in earth's history that a molecular structure such as DNA—which is a highly evolved and optimized molecule that must have undergone millions of years of evolution to attain its present level of sophistication and efficiency—couldn't have had time to arise and refine its abilities.

Earth, after all, is presumed to have been a hot, molten ball of fiery magma for much of its earliest history, with properties that preclude the existence of life in any form, even that of extremophiles. The earlier that evidence of organized life turns up, the more likely it is that panspermia was the source of that life.

Now a new discovery has pushed the origins of life back even earlier than expected. This is pretty cool stuff, making it more and more likely that the fundamental building blocks of earth's life originally arose on another planet... more than likely, even another solar system. Life may be a heritage that dates back to the first billion years or so of the universe, when galaxies were still forming... in which case life is approaching 13 billion years old, or something like that. Given the propensity for carbon to be the arbiter of all organic chemistry, that life may well have been DNA based... at which point we would have to say (I think you can see this one coming) that life is built into the very DNA of the universe.

LOL.

Of course, all kidding aside, this would be miraculous news indeed. If DNA based life is indeed an integral and inseparable part of the universe's character and nature, it carries what are perhaps nearly metaphysical implications.

Rotifers

Speaking of the persistence of life, etc., etc, How cool are these? 

enjoy!

the blog author has a new book out. recommended.

Redwing

For many years now, I've been watching the enormous flocks of redwing blackbirds that gather in the Piermont marsh. If one is there at daybreak, one frequently gets to see them take off — almost at exactly the same time, relative to sunrise, every morning.

 I would guess there are probably between 5,000 and 10,000 blackbirds in the marsh.  One of our favorite activities on summer evenings is to sit up on our deck in the Sparkill Gap (the first break in the basalt dike of the Palisades north of Manhattan on the west side of the Hudson River) and watch the birds come back to the marsh; never in the huge flocks that they leave it in, but always in tight clusters of 10 or 20, sometimes 30 birds. On rare occasions a larger flock comes back; but never the masses that leave together in the morning.

One of the phenomena that isn't recorded in the video above is a strange and striking moment that takes place just before the flock takes off in the morning. When one walks along the marsh in the darkness, say, about 5:00 AM, the birds are dead silent; I can verify this, because I've done it many times. But as soon as the first light starts to show in the sky, some few birds begin clattering — at first softly, but then in increasing numbers. As the light intensifies, the clattering gets louder and louder, until — after perhaps 20 minutes or more of anticipation — it reaches a crescendo. At this point, it often sounds like a huge, rushing waterfall in the immediate vicinity. If you come upon it and don't know what it is, you will certainly think it is the sound of a large river rushing over stones.

At this point, an extraordinary event takes place. All of the birds instantly stop making all the noise, at the same time. There is no tapering off; it's as though someone turned off a light switch, and the power went out.

Moments after that, they take off.

Listening to this phenomenon, I've wondered exactly what it is that triggers the behavior. Whatever it is, all the birds instantly sense it at exactly the same time, as though they were psychic; but of course, birds make relatively imperfect mediums. There must be a natural cue.

 I think what it is is the total volume or decibel level. There's a point, a threshold, that's reached; and when this threshold is reached, it triggers the flight behavior.

I've never heard of anyone studying this before, although it's possible someone has. In any event, it's one of those miracles one has to be there to fully appreciate.

This morning, my wife and I were there just to take off, once again. We watched impressive masses of birds wheel and dive over the marsh, circling while more and more birds peeled up out of the phragmites into the dervish black cloud above it. They behave as though they were a single organism; and this kind of behavior, where large groups of organisms take collective critical behavioral cues from a threshold of chemical signaling, is well known in the microbial world. The chemical signaling is one thing; but this audio signaling is another story, a signaling of vibrations.

One wonders whether there are bacteria who do something like this as well.

Microbes are forever

I've been making the point for some time about how incredibly durable microbial life is, but perhaps this particular article makes the point better than I can myself.

The characteristics of these microbes suggest that life is not only durable, it's incredibly durable. The assumption that life arose on Earth, which is practically an obsession with some biologists, is most likely a deeply flawed one. We can see from the temperatures and pressures that bacteria survive at that many different planets other than Earth, and sometimes quite unlike it, harbor the conditions in which life could arise. Life may not be special at all; life is, more probably, a default condition, something that arises almost anywhere it can. We can assume, instead of presuming life's rarity, that life is everywhere, that it is common, and that it spreads in the same way that... well, that bacteria do.

As I've pointed out before, and as Simon Conway Morris indicates in his fine book Life's Solutions, the DNA molecule is an incredibly sophisticated piece of machinery that, to all appearances, has survived millions and probably even billions of years of evolutionary pressure to arrive in the condition that it operates in in ordinary life forms. Because it has been on the planet since the inception of life as we know it — this is nearly certain — we have to stretch the imagination past the breaking point in order to  hypothesize circumstances in which a long enough timeline existed on earth for this molecule to reach its current fine-tuned state of evolutionary sophistication. My own gut feeling, on the whole, is that life arose on another planet, and another solar system, perhaps billions upon billions of years ago, and that it may have evolved many, many times over the course of the evolution of the universe.

Because carbon has unique properties, the argument most biochemists would make is that all life forms will be carbon-based, and that almost all of them will share molecular structures quite similar to the one we see in DNA. Biochemistry, you see, is subject to tight constraints given the laws of physics and chemistry; only so many things can happen, not everything. Once you stray from the tried and true, known proven principles of known biochemistry, you have to jump through incredible hoops in order to create a condition where life employs different molecules in order to work. As Morris points out in his book, the organic chemistry of life in Betelgeuse is going to look like biochemistry on earth.

 Not only that, most of the life forms will look like the ones we have here, especially on planets similar to Earth in terms of temperature and chemical structure. What we see around us is what works; leaves look like leaves because that's what works. Fish look like fish because that's what works. Tens of thousands of Hollywood alien movies notwithstanding, alien life is going to look pretty much like life looks here. That's because evolution continually produces the same solutions to problems within the same narrow range of chemistry and physics. If life evolves again somewhere else, its chemical structure will probably look like ours; and the physical organisms it produces will probably look like us as well.

Above all, what we need to do is cultivate a respect for the durability of these organisms around us, which we seem more interested, generally speaking, in exterminating than finding ways to live with. Our habit of attempting to exterminate bacteria instead of understanding them has led to a deepening set of problems that are going to be difficult to untangle; and we will address that in future posts.

Bacterial Bonanza!

No new post today per se, but A number of new articles are available at my resource web page on

gut bacteria and their effect on the human body.

Thermal ranges and microbiota

Temperature has been much in the news over the past few years. It's becoming apparent that no matter how much clamor the deeply misinformed far-right climate change deniers raise about it in the United States, the story is here to stay.  

We live within an extraordinarily tiny range of temperatures; a slice, so to speak, from the spectrum, as though we were a pair of eyes only able to see orange. Living organisms around us, in the meantime, have found ways to colonize a much wider (although still relatively tiny) range of temperatures; microbes (and, let's be fair, some larger organisms) are able to fully function from temperatures near freezing all the way up—in the case of microbes—to temperatures in excess of the boiling point of water. These creatures are called thermophilic organisms; and their presence in underground high-temperature waters, such as those found deep in South African diamond mines and at the mouths of undersea thermal vents, suggests that thermophilic microbe may well have been among the first life that evolved on earth, perhaps even the very first life.

Our presumptions about the temperature ranges and conditions life can function in have been progressively challenged over the past fifty years; microbes, it seems, can probably even survive the condition of interstellar space without losing the ability the thrive and reproduce if they make it to a new solar system. While the idea of intergalactic travel seems, today, impossibly remote, it seems to be reasonably certain that among the trillions of galaxies, ours cannot be the only one that supports life.

Life on the smallest scales displays a resiliency absent in larger forms. The conditions it needs to support it are, for one, far more focused. Nutrients can be derived from far more basic building blocks—even molecular ones— with far less obstacles to finding and assimilating them. The difficulty of procuring food, it might be said, is roughly inverse in proportion to size. Small creatures need little food; large ones need lots of it. Microbes, in this sense, have the decided edge in the competition for energy resources. They can live in marginal circumstances, subsisting on marginal resources; larger creatures need far more tailored environments, built on far more complex food pyramids. So microbes have the advantage not only in terms of temperature, but also scale.

We humans see ourselves as flexible in terms of temperature and scale; imagine ourselves as supremely adaptable to a wide range of environments. Yet microbes outperform us handily in this area, and they do so without any of the specialized equipment we require when operating outside our comfort zone. Speaking as regards to suitable habitat, we're actually confined to an incredibly narrow range of circumstances; even a tiny step outside them causes us to resort to protective clothing and vehicles. 

We think we rule the earth; but in reality the bacteria do. They live and reproduce in massive numbers in places we will never go; places deep in the earth, where life has found what are, to us, completely alien paths to survival. They share the same DNA, but their destinies diverged from ours billions of years ago.

Even then, some of them have developed novel approaches to DNA and reproduction itself; which shows you just how incredibly creative archaic microbes can be.

Soil denial

Cultivated boxwoods at Villa Lante, near Viterbo, Italy

Just after I wrote the recent posts on soils, the following article about soil degradation was posted on science news. I think it makes all the points I've been trying to make about soil quite effectively. The most important point, perhaps, is the widespread ignorance regarding this subject. Human beings are positively cavalier about their treatment of soil; and the soils we use for agriculture are only a fraction of the problem. All of the soils in suburban environments are being subjected to the same—or worse—indignities that agricultural soils are, and there are few to no controls being exercised.

No one educates children or the public on these matters, so we live in a culture of soil ignorance—in which no one really knows what soils do or why we need to preserve them—and soil denial, in which people think you can do anything you want to soils without creating long-term problems. Imagine a world, two hundred years from now, where trees won't grow properly anywhere in settled areas; where flowering plants struggle to survive and the green landscape we enjoy today is a thing of the past.

We can manage fertilizers; but bacteria are a far subtler proposition. Bacteria are best left to manage themselves; we need to become aware of them and help preserve and create environments that foster their growth and well being, not exterminate them wholesale.