Why are there so many species of bugs, but so few species of human?

Why are there so many species of bugs, but so few species of human?
Our past was like a scene from a Star Trek Episode: Ferengi (left) and Bajoran (right) character costumes from Star Trek, at the QTXP Destination Star Trek London MG. Credit: Wikimedia Commons, CC BY

Looking around at the natural world, have you ever wondered why some groups of organisms contain huge numbers of species while others are seemingly barren?

Take insects as an example, animals which evolved around 480 million years ago. There are perhaps 6 million living in all manner of environments, and occupying an incredible diversity of niches. Surprisingly though, they have never truly adapted to the marine environment.

Contrast this with Methanopyri, in the Kingdom Archaea, for which there is only a single species (Methanopyrus kandleri) which evolved close to 4 billion years ago.

This remarkable bacterium was found living on the edge of a 'smoker' under extreme conditions: 81-110 degrees Celsius, high carbon dioxide concentration and at a depth of 2,000 metres in the Gulf of California.

Just why some groups contain large numbers of species while others don't has long puzzled biologists. One of the main explanations has been geological age - older groups of organisms are more diverse because they have simply had more time to accumulate greater numbers of species.

Yet, the fact remains that some comparatively young groups of species are remarkably diverse; and conversely, some like the Methanopyri are very ancient but species poor.

A new study by Joshua Scholl and John Wiens published in the Proceedings of the Royal Society B has taken a fresh look at this age old problem.

They looked for the first time ever at the rates at which new species were formed across the entire Tree of Life, rather than just a subset of organisms as has been the focus until now.

They found some remarkable and fascinating patterns that shed new light on the question of diversity and its possible causes.

Over the course of life's history, plants have had a species production rate more than twice that of animals, while complex organisms (multicellular eukaryotes) have produced new species at a rate almost 10 times that of simpler one (protists and prokaryotes).

The work could also help explain another long held mystery: why did sexual reproduction evolve? Sex seems to have been a major catalyst for increasing the rate at which new species formed, perhaps explaining its success as an evolutionary strategy.

Among the vertebrates, a terrestrial lifestyle seems to explain greater species diversity. While simply living in a marine versus non-marine habitat might be the major reason for high species number in some major invertebrate groups, like molluscs.

Back to insects, adopting herbivory was probably the key to explaining high rates of forming in the past and their remarkably diversity today.

All of this made me pause and reflect on our own group of species, the two-footed apes, or hominins, and our incongruous existence today.

It's striking that we find ourselves alone, especially when we contrast this with the remarkable diversity of hominins seen in the past. Might this tell us something about humans today, and perhaps even where we might be headed as a species?

Our broader biological group, the Order Primates, contains the lemurs, lorises, tarsiers, monkeys and apes. There are around 350 species of living primates in a group that evolved perhaps 80 million years ago. Today, we're quite a diverse lot, with primates representing somewhere around 5 per cent of the total number of mammal species.

In total, there must have been many thousands of over the course of that time, nearly all of which have gone extinct. Extinction is the norm in evolution, with estimates of around 99 per cent of all life having disappeared. Same probably also for primates.

Tragically, half of all living primate species are threatened with extinction, and all of our close Great Ape cousins - the orangutans, gorillas and chimpanzees - are regarded as endangered or critically endangered by the IUCN.

By far the most diverse primates are the monkeys, particularly the Old World monkeys, naturally inhabiting Africa and Asia. They essentially evolved as a group about the same times as we hominins did, in Africa after 10 million years ago.

And some monkey species evolved over just the last couple of hundred thousand years, like Homo sapiens did, while others evolved several million years ago, just like some of our extinct relatives such as Homo erectus which existed from around 2 million to perhaps 50 thousand years ago.

But unlike the monkeys though, today we're alone. The sole surviving bipedal ape. Yet, there are probably many more species of Old World monkeys now than at any time in the past.

Why have we gone the opposite way of the monkeys? Species poor, not species rich?

Just 40 thousand years ago we humans shared the planet with several closely related hominins: like the Neanderthals, Denisovans, perhaps the Red Deer Cave people, and even archaic species in Africa.

It was kind of like an episode of Star Trek, with humans, Klingons, Vulcans, Cardassians, Ferengi and Bajorans all coexisting. Keeping each other in check ecologically, competing for resources, occasionally even mating with each other.

So, why are there still so many monkeys, but only one bipedal ape? Um, no idea, actually.

It's no exaggeration to say this is the greatest mystery of human origins, and one of the most important conundrums of science today.

What we do know though is that we humans belong to a highly extinction prone group of primates. We've gone from a total of at least 30 species - with, I predict, many more yet to be discovered - to one. And in just 10 or 20 thousand years.

From a world in which there must have been half a dozen or more bipedal apes coexisting at any one time - across the 8 million years of our evolution - to just us; solo.

The question we need to ask ourselves today is, which kind of species are we? Are we in it for the long haul, or will be disappear in the blink of an eye of evolutionary time as well?

I must confess that I'm an optimist; in the face of some incredible global scale environmental threats, mostly of our own doing, I'm not on the side of the extinction of Homo sapiens.

But I do think future generations are in for a pretty rough ride, and will look back on today and ask the question, why didn't you (we) act sooner to lessen our impact on the planet?

The answer might be difficult to face, especially if we eventually find out that the real reason we're alone today, the sole bipedal ape, is of our own making; that Homo sapiens was as Homo sapiens is.


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Sep 16, 2016
It's simple. Genetically, there are traces of those other species, present in modern human populations. So it would be best to say that, simply, one of the species absorbed all the others.
Because humans are remarkably adaptive (being able to adopt cultural changes required to survive in very different enviroment before natural selection even starts to take place properly), and because humans never shied away from long-distance travel, geographic and ecological barriers don't apply for humans either.

Sep 16, 2016
This comment has been removed by a moderator.

Sep 16, 2016
80,000 years ago there was a major volcanic eruption that caused a genetic bottle neck.
Genetic diversity took a tumble for humanity.
It's a fairly good theory.

Sep 16, 2016
Even Dogs are Totally different from each other at least to look. They do not mind as long as they are somewhat equal in size. Real problem is that Dogs are seen online attempting Mating with EVEN Chicken. Big Deal there are several species of Microbes.
Most important issue at hand is to utilize them for our own good...such as for making of Biofuel etc., They still cannot compete with Oil drilled from deep beneath us!

Sep 16, 2016
I think as a general rule, higher lifeforms have fewer species than lower lifeforms. Also, apex predators have fewer species and then there is that suspected genetic bottleneck.

Sep 16, 2016
Maybe the future will eventually provide us with the answer

Sep 16, 2016
The current survivors are the offspring of the "chosen" people who remained after the killing of those deemed less desirable by the prejudiced "chosen" group.

Sep 16, 2016
Uh, because we're profligate tool users ??

And, from 'tool' to' weapon' is but a stone's throw...

Sep 16, 2016
Even Dogs are Totally different from each other at least to look. They do not mind as long as they are somewhat equal in size. Real problem is that Dogs are seen online attempting Mating with EVEN Chicken. Big Deal there are several species of Microbes.
Most important issue at hand is to utilize them for our own good...such as for making of Biofuel etc., They still cannot compete with Oil drilled from deep beneath us!

I just read Sandia National Laboratory work on Lignin Digestion for Chockfull of Abundant Energy using unusual Sphingobium Bacterium Sp.

Sep 17, 2016
The meaningfulness of such a question is disputable because the concept of "species" is actually not well-defined. For example, a common convention is that bacteria are considered the same species if there is >70% similarity under DNA-DNA hybridisation. Applying the same method between humans and chimpanzees yields 98% similarity.

Sep 17, 2016
The general difference between monkey and ape diversity is an open question, but monkeys do evolved a more modern and diverse set of teeth that adapts to diverse niches.

Nitpicks:

- The article confuses the general monkey/ape diversity difference question with the relative diversity of our ape branch. When it claims 30 lineages it is a splitter, and lumping would merge many subspecies to the H. erectus - sapiens stem.

- The wording makes a reader confuse the evolution of the recent Methanopyri extant species with the old group split.

Sep 17, 2016
Maybe it's just an issue with time, mobility and remaining locally static afetr a move wlsewhere. For a species to split there must be
1) enough time for the species to grow distinct over many generations without contact to the original stock
2) it must have been able to move somewhere where that contact does not happen
3) it must remain in a location where it can inbreed to fix traits

Humans haven't had the time (barely 80-100k years) and are currently far too mobile to create isolated niches (humans were on that way with some groups being isolated from each other in colder and hot climates, but that is no longer the case)

Sep 17, 2016
@Odins: You don't provide references, but if you tried you would notice that your claim is controversial, insubstantial and by no means the given fact as you make it seem: https://en.wikipe...e_theory

@Nik: The rate of violence is pretty much the same over ape lineages, as far as the bad data goes. But behavioral science, again lousy data, has shown that humans chose to cooperate more than chimps.

The best fact here is in my opinion the recent result that the surviving Neanderthal genome is rapidly weeded out due to ~ 40 % average less fitness. A huge difference, likely due to the bottleneck they experienced. Fitting that to the ~ 1 % genome remains and their 1/10 population density at the time the neanderthal and "modern" subspecies met, they merged as one sexual population. [Yes, we descend from hippies, "make twerk, not war".]

Sep 17, 2016
It's simple. Genetically, there are traces of those other species, present in modern human populations. So it would be best to say that, simply, one of the species absorbed all the others
'Absorbed'. You mean hunted to extinction don't you?

There were many species before tropical cromags emerged. But cromags were the most prolific of iterations, and possessed a superior command of technology.

They simply outgrew and overran anything in their path. And soon the world was full.

And because of their penchant for overpopulating, tribes continuously came into conflict over resources and space and as a result, less capable variations were quickly eliminated.

Not many places to hide on this planet.
neanderthal merged
Neanderthal had been living in temperate and subarctic regions for 300k years and as a result their reproduction became aligned with the seasons.

They could not replace battle losses as quickly as cromags and were hunted to extinction as well.

Sep 17, 2016
There's a possibility that there will be no human species on Earth at all before too long, but I suspect numerous more adaptable species - mainly bacteria - will adapt and survive whatever hostile environment we leave behind.

Sep 17, 2016
...which evolved close to 4 billion years ago.


Evolved from what, sterile rock?

Sep 17, 2016
BartV, you have no idea how good you are at making yourself look stupid. None whatsoever.

Here's your award.
*slow clap*

Sep 18, 2016
@BartV
Tell us about the clearly observable irrefutable attributes of any claimed "creator" as it created nature with the pattern of brutality in respect of survival with always "Eat & be Eaten" ?

Is this a loving god or a devil creating pervasive suffering ?

Is it a parent like carer that educates or a careless experimenter watching permutations arise & fail ?

Tell us BartV, without resorting to robotic religious rationalization, the very key attributes of a creator ?

Can you do it in a scientifically detached fashion ie. The same Scientific Method which has made
immense progress in last 300yrs or so after letting religions cause suffering for the previous 1000's
of years fail ?

Heard of genetic algorithms that, without the programmers needing to know any properties of the items, the programs produce outcomes just the *same* as if an intelligent designer "created" them ?

Also tell us why *all* claimed gods are such woefully bad & incompetent communicators ?

Sep 18, 2016
The one of many issues that "evolution" has is that the billions of missing links simply do not exist. We see only distinct species in the fossil record. No gradual changing of species over time
You've been talking to Kirk Cameron again haven't you? Is he the guy who taught you how to 'go around' your intellect?
http://creationis...html?m=1

Reason is a whore isn't it? Ask Luther-

Sep 19, 2016
Insects evolved in isolated areas, compared to humans which traveled. Insects evolved specifically for their environments, very narrow evolution. Humans didn't, they mixed. Insect migration on a large scale never happened. Their widespread dispersion only now happens because people shift them from one place to another.

Sep 19, 2016
Isolation accounts for the great diversity on land where as the oceans are linked. One species of man? Our mobility..

Sep 19, 2016
80,000 years ago there was a major volcanic eruption that caused a genetic bottle neck.
Genetic diversity took a tumble for humanity.
It's a fairly good theory.


This accounts for [i]Homo sapiens[/i] in Africa, but not for the rest of the members of the genus [i]Homo[/i] . It is not clear if the Toba super-eruption caused [i]H. erectus[/i] to dissapear, but this certainly does not account for [i]H sapiens neandertalensis[/i] (while I'm not sure if we could count these as a separate species).

Sep 19, 2016
A Quick Though Experiment will give you the answer: What would you do if there were an Ape-Like, Intelligent Species, that was competing with us right now? Think the latest Planet of the Apes Movies. Well now you know, we would destroy them. They would not be tolerated. We would deem ourselves superior and eliminate the threat. And Done.

Us Humans do not take kindly to any threat, and we are very, very effective and destroying any threat to our survival. Just like Bears, Wolves, Lions, Sharks, or other apex predators that exist and pose a threat to us, have had their populations reduced to much lower levels. Only in recent decades have we helped conserve these animals. Basically we are so good at killing other species that threaten us, that we have to make laws to keep us from totally killing all of them.


Sep 19, 2016
A Quick Though Experiment will give you the answer: What would you do if there were an Ape-Like, Intelligent Species, that was competing with us right now?.


If they're competing with us right now, they probably evolved observing us.
And then? Would they be stronger than us? Smarter than us? Would they try diplomatic actions? Go full Air Strike Storm?
We can't prophetize on how it would turn out that easily because a movie was good to watch (?).

Sep 19, 2016
Think about the Native Americans. Europeans were not necessarily more "evolved" than they were, but did have a technological advantage. We competed over land and resources, and the European settlers almost completely wiped them out. And this was not that long ago. Do you think ancient Humans would not do the same when faced with competition from another species, even if it was a similar species to human?

Sep 19, 2016
A Quick Though Experiment will give you the answer: What would you do if there were an Ape-Like, Intelligent Species, that was competing with us right now? Think the latest Planet of the Apes Movies. Well now you know, we would destroy them. They would not be tolerated. We would deem ourselves superior and eliminate the threat. And Done
You're Dutch aren't you? I hate the Dutch. A nation full of thickheads and boors. Every single one of them.
https://youtu.be/QJ882QYzr-M

To humans the tribe next door is always a little less human. See 'little big man'. What makes you think related species would be any worse?

Sep 19, 2016
If they're competing with us right now, they probably evolved observing us.
And then? Would they be stronger than us? Smarter than us? Would they try diplomatic actions? Go full Air Strike Storm?
Naw we would give them all the power they want by promising us everything we ever wanted. It would be easy.
https://youtu.be/KLop4NUxsQs

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