Watching the Tree Grow
In larger science, one sees the general picture of our evolutionary path, and the species past and present in our biosphere. The biological tree continues to grow newer branches, and that new species develop, populate, overtake, disappear to successive species through time. The legions practicing sciences build knowledge continually and reveal detail about the splendor of the tree of life that is our planet. It is breathtakingly rich.
There have been hundreds of millions of species that have appeared and gone over billions of years, leaving the 8.7 million we share the planet with today. Together we are the eons-long dance, morphing in and out of species, adaptations, mutations. Some are fragile and easily lost (dodo, giant panda), while other species are highly adaptive and successful (trees, birds, humans). Like our own lifetime, species are born and eventually disappear, their residual memories leave varying degrees in the lifeforms that continue.
Most of us accept this conceptual transition between species without much sense of the transformations. Evolution is presented in a binary way, switching in time from one to the better species in a linear progression. We envision one species, eventually producing a second, like a generations-long cell division. It is presented that newer species start with genetic attributes which provide enough advantage that when expressed find favour, become prevalent and, with isolation becomes distinct from their parent.
With the sheer volume of species, genus, family, order, class phylum, it is understandable that the progression of one species into another is less clear. Yet observation reveals indications around us that are evidence of such changes.
Biological division and classifications of species is continued into species’ population studies within the species, down into the individuals with the varied feature sets. All breeds of dogs are a species, all horse breeds belong to a species. It is the individual differences in any species that are early indicators of evolutionary adaptation. Bigger tusks, shorter ears, nutritional allergies speak to variation.
Eventually distinctions lead to new species in populations that have been isolated from others, such as the seven million years that separate Asian and African elephants, species which can no longer interbreed. (Motty). Another example is the genus Equus from which all horses, zebras and donkeys originate some 4 – 5 million years ago, a species group that can still produce hybrid, but sterile offspring, that cannot reproduce.
Pulled to a shorter interval we have in the canine family, Coywolf is a recent, successful canid hybrid, bridging the 100,000 year species bridge between wolves and coyotes. This indicates that close species can be brought back together and their hybrid is a new species. The isolation and recombination of species, races and breeds is a central factor in evolution.
A recent study it is understood that evolution has happened in a new Galapologos finch species which began breeding endogamously in 3 generations, rather than 100’s of generations, as previously understood. Such rapid speciation suggests the actual morph events can respond quickly to new environmental conditions, but seen in the backdrop of millions of years, where such conditional changes are infrequent. \
A tectonic earthquake, or volcanic event may separate populations suddenly, which could trigger a species adaptation. Add isolated population bottlenecks and one can appreciate that the trigger initiating speciation can be a relatively short burst of activity that may settle into millenia of adjustment and refinement.
It should reason that the evolutionary map of species develops at a similar tempo as the climatic development of the the Earth. This would be long periods of relative stability interspersed with upheavals of varying regional and global magnitudes.
Modern Human Gene pool
For contemporary humans, genetic isolation can no longer happen in our easily-traveled world. Paleontology is discovering that multiple, eons-long waves of humanoid species out of Africa contribute to today’s human melange, a product of a complex genetic soup of evolving humanoid species.
When Homo Sapiens first appear in Africa up to 300,000 years ago, and later spread out of Africa, they encountered other humanoid species, such Neanderthal and Denisovans, among others hominim subspecies with 40,000 to 1.9 millions years between them. These other types themselves arrived in various geographies to find earlier groups of hominids. It is in these long periods of isolation and interaction that humanity finds its ancestry.
The following are hominids which may have been contemporary and had opportunity to add their genes to today’s humans.
The entire known history of humanity is 7 million years old from Sahelanthropus tchadensis, Australopithecus afarensis (5 million years ago), Homo habilis (2.5 millions years ago), and homo erectus (1.9 million years ago). East Africa and possibly other geographies provided sympatric coexistence for H. erectus and H. habilis for several hundred-thousand years, which further supports the more diversified process of evolution.
How much homo sapiens and sympatric humanoid species interbred is unclear, but the opportunity, and likelihood is there. This image collection above shows how humanoids such as homo erectus and homo habilis developed multiple subspecies in their geographic isolation. It must be remembered that such development would have been done both inside and outside Africa.
It shows that multiple subspecies can develop and exist in geographical proximity to one another. It suggests that isolated subspecies and estranged populations of hominids may have split away and been recombined in a number of ways over millions of years. Such mixing would have led Homo Sapiens to localize according to the subspecies encountered.
The mighty volcanic and its human bottleneck
The apocalyptic Toba super-volcano eruption in Indonesia (c. 70,000 years ago) has some suggesting a bottleneck of the human population. This proposes a human population of only 10,000–30,000 non-African individuals that survived the extreme environmental change around the Arabian peninsula.
There is evidence pockets of population survived the event in various geographies. Low numbers and difficulty with frequent glaciation would keep localized groups isolated for possibly long periods of time. Population bottleneck promotes many more individuated genes from survivors of various localities. Given the extensive spread and depth of humanoids, this could have brought many distinctions to prominence.
read : Out-of-Africarabia
Expanding the human habitat, again
If we consider the human species on the cusp of visiting and settling off-world, distinct habitat conditions would push towards adaptation, while isolation could eventually keep those changes away from other humans in other corners of the solar system or galaxy.
A smaller world with less mass and gravity would produce taller individuals, whereas a larger world with more gravity would see stronger bodies. Water worlds, desert worlds, those with intense solar radiation; little or high atmospheric pressures, exposure to different gas, element, molecular, microbial mixtures; any and every place would be unique in its offering.
It may happen quickly that humans and sybiotic species colocated in isolated, environmentally diverse locations would begin to modify, and could quickly go as far as becoming new species. Think about the person, who was born and lived entirely in the 1/3 Earth-gravity of Mars. Such a person would probably require serious physio-therapy, or prosthetic aids to be able to withstand their weight being tripled when visiting Earth.
It is unlikely that it will take hundreds of thousands of years for humans to begin to diverge quickly, as the potentially severe new conditions pressed on our physiology. Plants and animals given new environments will either adapt quickly, or not succeed. A few hundred years of celestial body separation will likely be enough to see a dramatic differentiation of species that once originated on Earth.
One easily understood concept of evolution is the sudden reduction of many species in the biosphere which allows for the rise of new opportunities and adaptations. Faced with a vaccuum, a smaller, but advanced biosphere blossums after a period of retreat or stasis. This is similar to the burst of life that follows a forest fire, or more regularly, after winter.
It should also be noted that when populations are small, natural selection actually becomes weaker, and the effects of randomness grow more powerful. A devastating event may see survival species as ‘superior’ in their traits, but still have a small population stock to grow and evolve from.
Many agree that a cataclismic asteroid strike on the Yukatan pennisula 65 million years ago led to the extinction of most dinsaurs and reptile species. The rise of mammals and grass plants was to follow.
But it was already the fifth such extinction. The others are well listed by Extinction Events – BBC
- The third largest extinction in Earth’s history, the Ordovician-Silurian mass extinction had two peak dying times separated by hundreds of thousands of years.During the Ordovician, most life was in the sea, so it was sea creatures such as trilobites, brachiopods and graptolites that were drastically reduced in number. (443 million years ago – 85% of marine species lost)Three quarters of all species on Earth died out in the Late Devonian mass extinction, though it may have been a series of extinctions over several million years, rather than a single event.Life in the shallow seas were the worst affected, and reefs took a hammering, not returning to their former glory until new types of coral evolved over 100 million years later. (375 million years ago, 75% of species lost)The Permian mass extinction has been nicknamed The Great Dying, since a staggering 96% of species died out. All life on Earth today is descended from the 4% of species that survived. (251 million years ago, 96% of species lost.)During the final 18 million years of the Triassic period, there were two or three phases of extinction whose combined effects created the Triassic-Jurassic mass extinction event. Climate change, flood basalt eruptions and an asteroid impact have all been blamed for this loss of life. (200 million years ago, 80% of species lost.)The Cretaceous-Tertiary mass extinction – also known as the K/T extinction – is famed for the death of the dinosaurs. However, many other organisms perished at the end of the Cretaceous including the ammonites, many flowering plants and the last of the pterosaurs. (66 million years ago, 76% of all species lost.)
Bottlenecked species surviving mass-extinctions is a repeated theme in evolutionary science. Understandably large, complex species are most drastically impacted, while smaller, or more versatile species have a better change to start new species clusters. The retained variances in a smaller surviving population will become the prevalent features in the new.
Biome pockets of life manage to struggle an existence during and after these extinctions, which leads to a pulse of new species, breaking out into new opportunities. Animal species usually depend on the extent flora has penetrated a region. Fewer plants means the geography can support less animal life.
Today we are Noah, looking for a path forward from the Holocene extinction of our times. This time around, a sentient species is challenged to survive it, a species that needs to preserve itself and support species.
Typically, ‘recovery’ from mass extinction events typically occurs over 10 million years or more. It is to be seen whether humanity survives this current extinction event. If we do, it will be an interesting to know whether the advantages and advances of our species in understanding and manipulating our own environment will spur Earth’s life to other planets and systems.
Either interstellar humans will find ‘life’ commonplace in the many kinds of locations, or they will bring life to the places where they set up. It will be interesting to find out, but we will not know for centuries, millenia, or more.
Life-changing conditions for Evolution
Beyond the catastrophic extinction events which kill off most life, and set up opportunities for survivors, a more accessible evolutionary model revolves around adaptation as the main driver of evolution.
One of the greatest changes life brought to Earth was the introduction of high levels of atmospheric oxygen. The Great Oxygenation Event (GOE) some 2.4 billion years ago introduced oxygen into the oceans and atmosphere. Cyanobacteria was the original phylum of species to produce this oxygen.
As oxygen levels increased, cellular specializations known as eukaryote developed, distinct from the single-celled lifeforms dominated up to that time, and even today. This new cell type leads to animal and plant species. Eukaryote cells developed plastids (1.5 billion years ago), the cell type found in plants and algae, and contains chlorophyll can carry out photosynthesis.
“oxygen levels in the environment, and the ability of eukaryotes to extract energy from oxygen, as well as produce oxygen, were key factors in the rise of complex multicellular life. Mitochondria and organisms with more than 2–3 cell types appeared soon after the initial increase in oxygen levels at 2300 Ma. The addition of plastids at 1500 Ma, allowing eukaryotes to produce oxygen, preceded the major rise in complexity.”
Eukaryotes and cellular specialization enabled a single lifeform to have symbiotic, mutually beneficial collections of cell types. Multi-cellular plant life opened the door to larger and diverse animal life.
Interplanetary – Interstellar Speciation
The idea that lifeforms may be transmitted from planet to planet, or even between star systems is being to settled. A large meteor or astroid strike on a planet with life can potentially blast a large mass beyond the gravitational pull of the planet. The Allan Hill meteorite found in 1996 in Antarctica and originating from Mars opened the debate whether it contained life.
More importantly inter-celestial fragments opened the notion that large meteor or asteroid strikes on Earth would carry chunks of the earth with its lifeforms to space. Studies show that some species could survive interstellar flight, such as the small water-bear (tardigrade), nematode worms, cynobacteria, spores, or seeds. It has now been discussed that the diversity of life on Earth can be transferred off the planet when high atmospheric dust is knocked from gravitational orbit by charged particles and set on its way to other planetary or even interstellar bodies. Large volcanic activity can list participate in getting masses of dust, debris with varying fauna/flora into the upper atmosphere.
We currently believe life to have originated naturally on our own planet. The process has yet to be duplicated by scientists, so it is certainly a rare event.
The possibility that life could move from one planet to another means than the natural process by which life arises from non-living matter (known as abiogenesis) need not happen in every system that has or has had life. It could have come from elsewhere and created a new biosphere from a small biological sample that landed on another celestial body with favourable conditions.
The most recent large meteor impact took out the dinosaurs some 65 million years ago. The escape velocity of Earth is 11.2 kilometres per second (approximately 40,000 kph). In the 570 billion hours since that event, material ejected from the Earth at the lowest velocity could have traveled over 2000 light years. High-speed meteors have been seen going as fast as 72 kilometers per second, extending the range to 15,000 light years.
If a large meteor strike were to have thrown biological material into space during the much earlier Ordovician-Silurian mass extinction some 440 million years ago, when another asteroid strike may have been responsible. Fast-moving material from such an ancient event could have covered 100,000 light years, and reached every corner and beyond the galaxy. The Milky Way galaxy has 100 – 400 billion stars.
Number of stars within 250 light years = 260 000. Within 5000 light years, there are approximately 300 million stars; the number of stars within 50,000 light years = 200 billion, our Sun is 26 000 light years from the centre of the galaxy.
Between large fragments created occasionally by asteroid strikes, and cosmic particles scraping atmospheric dust on a continual basis, Earth may itself be responsible for a panspermia of the entire galaxy, and could have reached different targets with material from various geological time periods in Earth’s life. Hundreds of millions of years after any interplanetary specimen successful hosted on other hospitable celestial bodies, the local biosphere could be as profound and radical as Earth.
As the discussion of the ALH84001 meteorite speculated whether life on Earth could have come from Mars, it is also to be considered whether life may have come from outside our solar system. If abiogenesis happened on Earth, it’s likely to have happened elsewhere. The make-life conditions may be so rare that it is quite infrequent but our study of life on this planet shows it to be resilient to cataclysm. A bacteria rich planet blasted in a supernova may, over hundreds of millions of years spread life to thousands of galactic bodies. Maybe ur-life on Earth came from an event outside our system which is why we can’t quite duplicate it. Earth and possibly most other life-bearing planets in the galaxy could already share a mother, an extended life family across star systems.
The web of life is vastly more complex than we understand it today.
Sizing Up Species
It could be argued that early cyanobacteria, its addition of oxygen and subsequent yearly glaciation contribute to the development of a global life form, as expressed in seasonal flux. It is argued that until adequate oxygen was available, the Earth was largely ice-free.
Bringing down atmospheric carbon dioxide levels, and raising the oxygen levels led periodic glaciation starting with the 300 million year-long Huronian glaciation. (see blog entry – Before floods, there were puddles).
The slow change in oxygen levels allowing frozen Earth eras did not impact the planatery biosphere in such a sudden way. The transition did help mold life into cooler adaptations, and more diverse multi-cellular structure.
Cold oceans allowed nutrients deep in the ocean to more easily circulate to cool sunlit surface waters, unlike a warm water blanket which repels the upswell.
Cold water can also hold more dissolved oxygen than warm water. More oxygen and food allowed animal life to thrive, a phenomena still seen today in arctic/antarctic water.
Seasonal light variations are also drastic as polar summer days can last weeks, or months, unlike the regular 12 hour daylight at the equator. The light means continual photosynthesis and growth.
In nutrition-fortified, oxygenated, well-lit seas, plant life explodes. Masses of zooplankton flourish allowing legions of fish and seabird to thrive. On land, cooler, drier climates kept vegetation from growing into a jungle-heap. Sparse forests, open woodlands, and savannas promotes animal mobility.
Bergmann’s Rule describes how larger animals benefit in colder climates since smaller surface area-to-volume ratio minimize energy requirements. Advantage is given to size, as large fauna more easily keep warm, can go longer periods without food, and have greater protection from predators.
Many are familiar how ice ages since the dinosaur extinction shaped large land and marine mammals into what is known as the Pliestocene Megafauna.
Human punch and dodge (features, adaptions, mutations)
Closer to human history, evolution has both bottleneck and adaptive processes playing a role in the development on our species, our cultures. Looking at some of these actors, we can begin to see how our own actions play a role.
Homo Sapiens have existed as a species for 200-300K years. During this time there have only been human civilizations for the last 10-15K years. It may well be the case that humans had to build themselves and survived conditions that would allow civiilzation to grow from their initial lifestyles. Disease-resistance and social convention are requirements developed as humans begin to live closer together.
It should also be remembered that the human population at the end of the last ice-age and the beginning of civilizations was about five million. The thousand+fold human population explosion to seven billion means many genetic variables will find their place in the species at a more much quicker rate.
Fire & Smoke
Over the last million years since man first controlled (and fell in love with) fire, there is evidence suggesting humans evolved the ability to better tolerate smoke, as well as the gastro-intestinal ability to eat charred meat and vegetables.
We have long set fires for the hunt, to clear brush areas to promote fresh growth, to heat, transform, protect. The human eye knows the profound mystery of watching a flame, whether candle or inferno.
Cooked food gave rise to a reduced need for large cutting and grinding teeth, and less of a diverse need for bacterial culture to resist illness caused by rancid food, and food preservation made possible more free time.
Language and Music
Spoken language may coincide with the speciation of modern humans. Some argue it may have been the fireside leisure. Entertainment is humanity’s first currency. Like the notion that beer predates bread as a use for wheat, it’s probable that music came before spoken language.
“(I)t appears probable that the progenitors of man, either the males or females or both sexes, before acquiring the power of expressing their mutual love in articulate language, endeavoured to charm each other with musical notes and rhythm.” (Darwin, 1871, pp. 880)
Language and music also evolve over time. What certainly started as body movement and simple sounds has become thousands of languages and musical styles.
Modern music styles such as rock or jazz, as well as modern languages with thousands of words probably could not be appreciated by humans until recently.
The vocabulary of small pockets of people such as craftmen, hunters and healers eventually gets picked up by the general population as part of the lingua franca.
In the Holocene era, regional languages and dialect are set to see large scale extinction as more humans communicate using common languages and families no longer remain in close proximity to one another.
Urban Microbial Tolerance
The rise of settlements and later cities has been made possible because of the heightened tolerance to infectious diseases. City-dwellers have spent centuries and generations in proximity and variously exposed to diseases brought to them from travelers.
Small pox, cholera, TB, typhus all took their toll on the population. Over generations these outbreaks would end, and individuals with higher tolerance to some of these diseases would become more prevalent.
The bubonic plague of middle-age Europe reduced the human population by a third, and much more in certain cities and districts. Recovery from Black Death led to increased optimism, mercantile and artistic, and opened the way to the modern era.
Humans did move into many geographies, and in doing so, limited the overall impact of all but the most global events. More recent, and more geographic, selective cataclysms lead to cultural evolution.
Another more recent volcano was the Thera eruption on the island Santorini approximately 1600 BCE. Sixty cubic kilometers of rock blasted from the largest eruption in ‘recorded’ history, and certainly led to the destruction of the nearby city of Akrotini (possible source for Atlantis story), and a weakening of the Minoan civilization, which enabled the late bronze age conquest of Mycenaean Greece.
The conquest does lead the Mycenaean to coopt many Minoan cultural artifacts. This cultural ‘leg-up’ gave rise to Greek
Human wars have disrupted and destroyed many known human civilizations and countless unknown settlements. It also acts as a catalyst to potential post-war social renewal.
Developments in warfare capability are similar to genetic experience that provides advantage to a segment of a species population. Cultural development, spread, appropriation, and destruction are impacted by war, a manmade climate-changer.
The move from softer copper to the harder (copper/zinc alloy) bronze 5000 years ago, during the Neolithic – agricultural revolution, was a move away from hunter gatherer, “the original affluent society” to state warfare, armed policing, social castes, feudal nationhood, agriculture crops, taxation & slavery.
Metal weaponry allows the strongman to push their agenda on to those not otherwise interested, or even actively resisting. History is full of the strong men with armies. The charismatic look to impose themselves over others.
The power and changes of advanced weaponry is seen again later in the Bronze Age collapse where the iron and steel change long established power structures, civilizations and dynamics.
Like the only human in the room with a spear, a torch, a blade, a sword, a gun; it gives might to those powerless without it. What follows such civilization collapses is an unprecedented new age that would not have been possible otherwise, similar to the regrowth following a forest fire.
Features & Cultures as Drivers
Ultimately a species is a collection of individuals that span generations and various genetic expressions that may or may not be a biological advantage.
The mutation of brown eyes to blue represents neither a positive nor a negative mutation. It is one of several mutations such as hair colour, baldness, freckles and beauty spots, which neither increases nor reduces a human’s chance of survival. As Professor Eiberg says, “it simply shows that nature is constantly shuffling the human genome, creating a genetic cocktail of human chromosomes and trying out different changes as it does so.” – University of Copenhagen. “Blue-eyed humans have a single, common ancestor.” ScienceDaily, 31 January 2008.
Given there are blue eyes in dogs and cats, we can assume the blue eyed experiment is somewhat common.
The biological advantage may not always play the central role in the success of expressed genetic features. It is ultimate sexual selection determines how prevalent a random feature will become. The first blue-eyed human /dog / cat obviously was accepted and found expanded favour across generation in the local population.
The definition of common beauty and desirability within a cultures is a key driver in societies. Societies’ selection processes that over centuries molds distinct cultural groups. Trends, not individual choices will determines the prevalence of features. One example is Japanese integration of facial hair into their culture, while Chinese culture has less overall interest in it.
Trade and warfare bring societies and cultural features into contact with one another, sometimes one dominating and expanding, while others decline and are largely forgotten.
Technology driving our development, our evolution
Our current explosive growth drives innovation and challage in every field and species. In two or three generations, humans live longer, healthier and taller, albeit more stressful lives than societies before. But our species’ voracious appetite for affluence may cost us and the biosphere more than we can withstand.
We are more technically capable and driven than a century, a generation, a decade ago. We have three times the people, millions of people giving their intelligence to thousands of projects, questions, problems. It won’t be long before there are many easy solutions to numerous issues. How to ensure balance in 7 billion?
The Earth will survive humans, so this struggle is only the self-preservation of our species and the species that cohabitate this planet with us. We must make every effort to ride and tame the extinction tsunami we are now riding.