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Saturday, April 12, 2014

Self Destruction

We seem hell bent on wiping ourselves out or at least wiping out the relatively comfortable, interesting and fulfilling life we have now.

The sooner we admit that we are not as smart as we think we are the better.  Then we might be able to do something about it.

Until recently, the peak of our ecological knowledge dictated that if we wipe out the wolves, we will have more deer to hunt.  Read Farley Mowat's book Never Cry Wolf for a very comical treatment of this myth.  I bet most people "on the street" would still think that this is perfectly correct.

We are wiping out species at a rate equal to or greater than during the past 5 great die offs with gay abandon and with little appreciation of the consequences.

Up until recently the commonly held belief was also that  if you kill all the whales, there will be more krill for fish to eat and hence more fish to catch.  I bet if you asked "the man in the street" you would find he would agree with this also.  We are woefully ignorant and the sooner  we realize it, the sooner we may be able to do something about it.  So what can we do.

Once we have admitted our own lack of knowledge and moreover, our venality in the collective (corporative greed), there is only one solution.  We must have large areas which are set aside for nature to get on with what nature does best.  Managed parks such as Kruger in South Africa and all the various other parks in Natal and elsewhere are valuable but there must also be completely untouched areas.  To give you an example. In Kruger they used to collect dead wood for the fires in the camps.  The accepted wisdom was that this would have no effect on the ecology of the park.  This was stopped when some bright ecologist realized that dead wood is the base for a whole network of organisms.  Wood is a polysaccharides.  In other words, a chain of sugar molecules joined together in such a way that the giant molecules are insoluble and refractory to most multi-celled organisms.  Only bacteria can break down the cellulose and many multi-celled organisms have such bacteria in their gut.  In this way wood becomes a food source for a whole ecology.

Kruger now brings wood from outside the park.

If it took so long to realize something so simple such as the role of wolves and whales and of dead wood, just how competent do you think we are  to manage vastly more complicated interactions in nature.  We must simply set aside areas which we leave alone.

Look at the story of the return of the wolves to Yellowstone Park.  What a success.  For a really lovely explanation of how it works, go to TED talks and type in rewilding George Monbiot.  What a great talk.  Here again we have shown our incompetence and venality in our interaction with wolves.  If we can't get something so obvious and simple right, what chance is there that we will manage nature.  None at all.

And why should this lead to self destruction.  With most of us living in cities, we are pretty ignorant of the things nature does for us.  It provides clean air and water, food and fibre, sources of medicine and an array of molecules for testing which if efficacious can be synthesized and for that matter, why do we think that us, a latecomer in evolution, has the right to wipe out other species who were here long before us.  I wonder if every planet on which life exists eventually produces a species that wipes out the planet and itself with it.

I would doubt that we could wipe out all of humanity.  We are like cockroaches.  Very hard to exterminate.  Lovelock was laughed at when he suggested that within this century, human population would be down to 1b.  We are approaching 7b now so that means that 6 out of 7 of us won't survive.  He, of course, has no way of knowing just how serious the decline will be but what is pretty certain is that it will be the end of our technologically advanced civilization.  There goes the internet, the mass production of goods by robots which is only viable with a huge market, a sort of Pax UN (as faulty as it is) and so forth.  There goes also our effect on nature and she can begin to repair herself.  Then we will bounce back and do it all over again until we achieve total destruction.  Not a pretty picture.

There have been many many empires built up over the last 5000 years or so and all that remains of them is some archeological remnants and a population of struggling humans occupying the same territory.  On a localized scale we have turned bread baskets into desert.  The first people to arrive in new territory wiped out everything their technology was capable of destroying.  European man arrived and trashed whole ecologies.

Look at North America, for instance.  When Europeans arrived, they were overcome by the richness of the ecology of North America.  Of course they were comparing it with Europe which they had already trashed.  They had no idea of what existed there before the "Indians" arrived.  All that richness Europeans observed was only a remnant of the original pre-human fauna.

For the first time, we have a commercially connected world and we all breath the same air and depend on the same weather systems.  For the first time, as shown by the 2008 mini crisis, what happens in one location effects all of us and as the people in Western Canada will attest, the air pollution from Asia effects them.  The ice of the Arctic is disappearing at a rapid rate and prediction of the effects of an ice free Arctic are dire.  It's not that we couldn't live in at least parts of the world under the new climate that seems likely to occur.  It is just that we have used our technology to adapt ourselves to the present climate and have allowed our population to grow to an extent that we are balanced on a knive edge.  One failure of the grain crops of the Northern Hemisphere, for instance, would send waves of destruction around the world.

I'm afraid that what we need is a mid level disaster.  Nothing else will shake our system hard enough that we will do something about it.  Let's hope when we do finally wake up, that it is not too late.

Friday, April 11, 2014

The Malasian Airliner

I'm puzzled about the search for the Malaysian Airliner.  Once they had detected even a single ping on the towed array, I would have thought that they would have pretty well pinned down the location of the source of the pings.

Before I explain what I mean, I must admit that my "knowledge" of how these things work is based on novels by authors like Tom Clancey.  However, Tom was said to be a bit of an enthusiast on modern weapons and did his homework.  The basic premises were confirmed in other novels.

As I understand it, when an atomic submarine, either the missle carriers or the attack boats, are on patrol, they stream a long line behind them which is festooned with acoustic sensors (microphones).  I'll explain how they work with simple geometry but of course, the signals detected by these sensors are fed into a computer which gives a virtually instant firing solution.  And as far as I understand, a single ping from an enemy submarine or a noise such as propeller cavitation,will determine its position.

Lets look at the simplest situation in which the target is at right angles to the towed array and right opposite the middle of the array.  The pings arrive at the front microphone and the back microphone at the same time.  This tells you that the target is located somewhere on a disk that intersects the towed array in the middle and at right angles to the array.  In the case of a black box which is pinging, you know it is on the bottom of the ocean so the black box is on a line where the disk intersects the bottom.

However, you don't only have microphones at the front and back of the array.  Let's look at the microphone that is in the middle of the array.  It is closer to the target than either of the end microphones.  It therefore receives the ping before either of the end microphones.  The speed of sound in water is well known.  As the wave front of the ping moves outward, the circle gets larger and larger such that for an infinitely distant target, the wave front is essentially flat.  The difference in time becomes shorter and shorter the further away the source of the ping is located.  From the difference, with modern electronics you get an estimate of range.  In other words, our disk becomes the rim of a bicycle wheel and becomes a solution of the two points where the rim meets the bottom of the ocean.

Now it seems unlikely that all the microphones on the array are omni-directional.  I would assume that there are some directional microphones and the difference in the amplitude of the sound recorded by these various  directional microphones gives you a direction.  In other words, if the "bicycle wheel rim"  intersects the sea bed in two locations, this sorts out which of these is the target.

An added dimension is added when the black box pings for an extended time and the boat is towing an array of microphones.  You are getting a view from a whole bunch of different angles all pointing to a given location. 

The geometry is only slightly more complicated when the ping is in front or behind the array.  In one sense, it is simpler.  If, say, the ping is behind the boat and off to the side, the front and back microphone receive the ping at different times and this indicates in what direction the pinger is located.

Then you have the "passing train" effect.  The pitch changes if the train is coming toward you or has passed and is going away from you.  In this case, the listener is on the train and listening to a stationary sound.  Same effect.

A modern submarine is dependent on knowing exactly where an enemy is located and quickly before they can get off a torpedo.  I can't understand why the location of a stationary source of repeditive pinging is not pinned down almost instantly.   What is all this steaming back and forth over the location to narrow down its position.  They certainly can't be towing an array such as the subs use.

For that matter, why was one of the American or Russian atomic subs not diverted to the location.  Surly they would have pinned down the location within minutes of arriving on location.  Perhaps they have been.  For that matter, they could be pinging themselves and mapping the bottom.  Surly the echo from a bunch of scrap Aluminium would be different from the echo from a soft muddy bottom.

I don't get it.

Sunday, February 16, 2014


In case you haven't caught up with it yet, SkyTruth is going to create something of a revolution - a tool for actually seeing what is happening to our world in real time and providing the ability to see  changes over time.  I first heard about it from Michael Field of Fairfax on New Zealand National Radio on Friday the 14th of February, 2014.  He kindly sent me a transcript of the guts of what was talked about so rather than writing it out again, I have pasted it below.  It has been a long time coming since the beginning of the Satellite era but here it is finally. It is worth noting that you can't access it at present because the information is proprietary but this will change some time this year with the launch of a new satellite.

Shock at the scale of fishing in South Pacific

Michael Field
Fleets of sophisticated Chinese and Spanish fishing boats working the edge of New Zealand’s exclusive economic zone (EEZ) have been exposed by an American volunteer group whose work is creating a revolution to the environmental movement.
Fishing boats create picket fence lines on the edge of the EEZ around places like the Kermadecs and off East Cape, taking bluefin tuna, swordfish and orange roughy.
‘‘Most people would be gobsmacked by what we are finding,’’ geologist John Amos said from Shepherdstown, West Virginia, (pop. 805) where the group SkyTruth operating out of an office behind a draper’s shop.
They’ve also spotted an unusual 34-year-old Cambodian flagged tuna boat, Gral, leaving Suva, Fiji, and making straight for New Zealand’s Raoul Island despite having no licence, permissions or complying with normally strict quarantine procedures.
SkyTruth has been commissioned by the US based US$792 million (NZ$972 million) asset rich Pew Charitable Trusts to monitor what is happening around the Kermadecs, an archipelago 1100 km north of Auckland, home to one of the world’s most diverse marine life.
Pew has supported the Kermadec Initiative which is calling for a 620,000 sq km ocean sanctuary from the existing island reserves out to the EEZ.
SkyTruth use Automatic Identification System (AIS) satellite data transmitted from ships and satellite radar imagery to detect fishing boats that turn off or do not use AIS. 
Amos says they find many vessels ‘‘fishing-the-line’’ to catch valuable fish before the stock gets into New Zealand waters.
‘‘Not just around New Zealand, but also in Chilean waters, we see Chinese, Ukrainian and Spanish flag vessel fishing right up to the line.... You see this concentration of fishing effort around the line and you wonder how many of these migratory fish even make it through.’’
‘‘It is like a picket fence of fishermen.’’ Amos said they are producing a South Pacific map that will show the cumulative fishing that has gone on over a 12-month period.
‘‘That is the kind of thing we can do now,’’ he says, adding people will be shocked by what they see. 
New Zealand makes some money off the Spanish.
Last November two of the armada ships, Carmen Tere and Artico, were serviced in Whangarei. Their Indonesian crews complained of poor treatment at the time.
SkyTruth in the last couple of weeks has spotted Carmen Tere working a line off East Cape and Artico is on picket duty at the Kermadecs. A fleet of four Spanish ships is gathered in an area of orange roughy fishing grounds.Red baron
Most of their catches are taken to Papeete, or transhipped at sea.
With a new European Space Agency satellite, Sentinel 1, in orbit next month, SkyTruth expect a ‘‘stream of free radar imagery....
‘‘Clouds of data seems to be what we humans are good at producing these days, and using that is for good purposes.’’
It can identify problems in the EEZs and shows the sheer persistence of the fishing industry.
‘‘There is no place these guys don’t go.’’
SkyTruth first came to world attention when the White House used it to work out the scale of 2010’s Deepwater Horizon oil spill in the Gulf of Mexico.
Amos, 50, recently cataloguing the number and size of fracking operations, is a folk hero in the US.
‘‘You can track anything in the world from anywhere in the world,’’ Amos told the Washington Post last year.
‘‘That’s the real revolution.’’
SkyTruth’s technology edge was revealed when a 498 ton ‘‘fish transporter’’ Gral pulled into Suva on January 17.
Owned by South Korea’s ‘‘Aururoa Shipping’’ it had been called Arche until December – and before that the tuna longliner Gaia, Oryong No 332 and Sam Song No 507.
On January 20 it sailed out of Suva and made directly for Raoul, arriving at 2.55am on January 23.
Conservation Minister Nick Smith said he had not been briefed on Gral and referred questions to officials who could not provide information on it.
The Ministry of Primary Industries said ‘‘it had broken down and was undertaking repairs’’.
Amos dismisses the MPI line.
‘‘It appears that the moment they left from Fiji, (Raoul) was the destination.’’
Fuel was expensive and from watching marine traffic SkyTruth saw ships always went the straightest line possible.
A Tauranga ship, Claymore II, under charter to the Department of Conservation, earlier this month found Gral anchored in a bay they would use.
Its owner, Nigel Jolly, said before they left New Zealand, DOC rules required divers inspect the hull for marine life and a quarantine dog was run through.
‘‘After all those precautions we get a permit to go there, but if fishing boat or a visiting yacht seeks shelter at Raoul Island, no matter if it is a reserve, the law of the sea says it has a right.’’
They never found out what Gral was doing.
Bronwen Golder, director of Pew’s Kermadec Initiative, says SkyTruth under-scores the vulnerability of the area and the need for a marine sanctuary.
‘‘What this daily tracking shows is that there is constant international fishing activity just outside of New Zealand’s EEZ over extended periods and in fleets such as the Spanish,’’ she said.
SkyTruth has tracked Gral out of New Zealand’s EEZ and headed toward French Polynesia.
On the high seas late last week it rendezvoused with a Russian fishing boat, the 1137 ton Palmer which had switched its AIS off until the meeting.
On Saturday they remain within five kilometres of each other.
10 february 2014

Friday, January 31, 2014

Natural Selection and Evolution

This blog was triggered by an item I heard on National Radio here in New Zealand.  An ornithologist was talking about banding birds and how they band the common house sparrow.  Apparently they band them, both to learn about sparrows but also to give their people practice in banding small birds before they tackle rare and endangered species.  In the talk, he mentioned that with multiple clutches, a pair of sparrows can easily produce 20 young each summer season.  He also mentioned that the natural life span of a sparrow is about 10 years.

This got me to thinking how quickly a population of sparrows could grow.  Start with one pair and by the end of the year you have 11 pair*.  Next year these 11 pairs breed and you have 121 pairs.  In the third year these breed and you have 1331 pairs.  Let's go to 10 years which is the life span of the first pair.  You get up to `259,374,246 pairs.  Over half a billion individual sparrows in a decade.

*The 10 pair they produce plus themselves.

Now clearly, the only time that such an expansion could occur would be when the sparrow was introduced into a new environment in which there was abundant food, no natural diseases, no predators and abundant nesting sites.  Even then, this sort of expansion would be unlikely to continue for more than a few years.   No matter how large the food supply, the sparrows would soon exhaust it.

We actually observe that in any area where sparrows have been extant for a while, the sparrow population remains pretty much the same.  There are good sparrow years and bad sparrow years but overall the population varies around a  mean.  Let's assume for the sake of the argument that with the various factors working on the population, the average life span of the first successful breeding pair is actually 5 years.  We are being pretty generous here.  What this means  for the successful breeding pair, is that on average,  of the 100 babies that they produce over their life time (at 20 per year for 5 years), only one pair will survive.  If more survived the population would grow, if less, it would shrink.  That is a 98% death rate or more to the point, 98% don't get to pass on their genes to the next generation*.  This is natural selection.  It is huge.  Talk about survival of the fittest.  Sure some will succumb to random accidents that have nothing to do with their fitness but consider the sparrows that will survive to pass on their characteristics.  A surviving sparrow will likely have:

*In evolutionary terms, not passing on your genes is 'death'.

*Better disease resistance
*A beak that is adapted to cracking the seeds that exists in the region.
*An ability to utilize other food sources
*The same colouring as its fellows so that it doesn't attract the attention of Kestrils
*A great ability to choose safe nest building sites and to build good nests
*A very strong inclination to look after it's young.
*A flexibility in choosing nesting material and, nowadays,  being able to utilize human products.

and on and on the list goes.

Here we come to one of the main characteristics of Natural Selection.  Once an animal is pretty well adapted to it's environment, and the environment is unchanging, Natural Selection has much more to do with keeping the animal the same than it has to do with producing new varieties.  Most variations will be less successful than the standard and with the huge reaping of the young, only the best will make it.  Let's look at predation for example.

The Kestrel is known colloquially as the sparrow hawk for a very good reason.  It hunts sparrows and it hunts them on the wing. Our Kestrel is stooping on a flock of sparrows.  One of them is white.  How much easier it is for the Kestrel to keep it's eye on one individual bird if it is different.  If it keeps shifting it's focus from bird to bird, it is always chasing a fresh bird rather than the one it initially locked on to.  If all the sparrows were white then a dun coloured bird would be at a disadvantage but as long as the majority are dun, the white one will have a very limited life.  Think of Lions and Zebra's as another example. 

However if one beneficial mutation does occur which doesn't have a down-side, you can see how fast it could spread through the population as the carriers of this new gene out-compete the standard sparrow.

It's an interesting thought that the greatest enemy to a sparrow is another sparrow. We see the population staying more or less the same so  this enmity between sparrows is not apparent to our eye.  One sparrow does not predate another sparrow.  However they compete for exactly the same resources.  They compete for nesting sites, food, mates and so forth.   The successful sparrow passes on his genes, the unsuccessful one does not.

Even more so, if a huge number of ecological nitches are left empty after, say, a meteor strike such as occurred 65m years ago, evolution can go wild.  And as each new variety changes, it changes the environment for a range of species around it.  An environment is not only the trees and bushes and physical features where you live.  It also includes all the other animals in the vicinity that you prey on, the animals that prey on you and those that you compete with for food.There is an arms race such as occurs with humans during a protracted war.  Look at all the developments in a wide range of fields that occurred because of the first and second world wars.  Not only did we have the classic better shell, better armour, better shell better armour but also developments in medicine, radar, communication, aircraft technology and so forth.  The same happens amongst the animals and plants when they face a new environment. If they are sufficiently adapted to survive at all, they than undergo rapid evolution which better suits them to the new environment.  Darwin's finches are one of the best documented examples of this process.

Now let's assume that blown on the wind or brought on the feathers of a migratory bird, some seeds arrive.  These seeds are for a plant that has seeds that our sparrow could eat but only with a stronger beak.  The plant flourishes because nothing is eating it and eventually, with genetic variability, a sparrow is born that can use these seeds.  With a new food source that only he can utilize, his survival potential and his potential to produce surviving offspring who can also use this new food source is huge.  Remember, the potential to increase your population if there is a new food supply is huge.  The population of this new model expands very rapidly and since it competes with the older variety in virtually every field, it rapidly replaces the original type.  All we notice is that the beaks of collected birds of this species increase in size over a period and we puzzle over why.  In fact there has been a huge unobserved mortality amongst the standard variety.

We come now to the question of how much natural variability is available for natural selection to work on.  We study various populations over our life time and through the museum and even the fossil record and rarely see an animal that varies much from the norm so we assume that "sports" are rare.  We, however, only have to look at our domestic plants and animals to realize how wrong we are.  Look at all the dog breeds we have.  We replaced selection by nature with human selection and we can keep alive whichever varieties we desire.  In a few thousand years, starting with the wolf, we have produced all the breeds of dogs you see today.  The wolf hasn't changed much over this period.  He is constrained by natural selection to stay in the already well adapted form that he has had for thousands of years.  Our conclusion??

Given a change in the environment that favours a different type of animal or plant, evolution can occur explosively.  There will be lots of sports to choose from and the selection process is relentless.  The expansion potential for an animal or plant that can exploit a new opportunity is vast. This may be the explanation of what geneticists call punctuated evolution.  It is most likely to occur when something has changed an environment.  This can include:

*A disease or human intervention that wipes out a species, especially a key species such as the beaver, or the honey bee.

A cataclysm such as a large meteorite or mega volcano that wipes out the animals of an area.  But note here that some pretty large events can occur with no apparent effect on the make up of plants and animals of an area.  As long as some populations of each component of the ecology still exist, then after a bit of argy bardgy, they will pretty well re-establish the original ecology. 

*The introduction of a new species of plant or animal into an environment.  This can be causes geologically, when a continent such as India bumps into the under side of Asia (55m years ago) or when man brings a new animal or plant to an island or continent where it didn't exist before.

Something curious that emerges from this, very incomplete list, is that man can  have (and has had) a much larger effect than a major meteorite strike or a mega volcano erupting.

On a  time scale, much shorter than geological,  Natural selection / evolution has huge potential to create new varieties given the right set of circumstances.  In a well established environment, thought, it mainly works to keep everything the same.

Monday, November 4, 2013

The destruction of Planet Earth

Sorry, I just wanted to get your attention.  There is no way (well almost no way) we could destroy Earth*.  In the words of my second favourite comedian**, George Carlin, the world will be just fine.  We may not be here but the world will be hunki dori.

* I've included a way at the end of this blog but it is pretty far "out there".
**My favourite is Bill Maher

It's true we may bring nature to a state where there is no animal larger than a cat remaining on the surface but evolution will refill all these lovely empty ecological nitches and it will do it surprisingly fast  in a wild flurry of evolution.  In one or two million years, we won't recognize the place???

The first people who arrived on any uninhabited  island or continent eliminated a huge range of megafauna.  Most of it was done within a few hundred years.  Then when European man arrived with his modern technology, he destroyed and is still destroying whole ecosystems.

When Europeans arrived in, for instance, North America, Australia and New Zealand, the fauna they saw was but a pale remnant of what was there before the first humans arrived.  The first humans had wiped out anything they could eat.  Then European man got busy, trying, quite successfully, to eliminate even this pitiful remnant and doing his best, as well, to eliminate the first people.    Who eliminate who often seemed to depend on who had the best armoury of diseases that they, but not the other side, were immune to but that's another story.

About the only area that has retained some semblance of her megafauna is Africa and only because animals  evolved escape capabilities as humans improved their hunting techniques.  As our killing methods advanced, the more wary animals survived to breed.  Later European man, in South Africa, had almost eliminated Africa's megafauna when he realized that everything he held dear was about to vanish and set aside large parks and brought back the major megafauna that had survived early man. Once more under the first people but with European killing technology, the animals are on the way out again.

As long as we don't destroy too many animals there are all sorts of animals just waiting in the wings to appear and fill all sorts of empty places in nature at a rapid rate.  I know that sounds pretty strange so let me explain.

Let's use the tail of a monkey as an example.  Our monkey has a prehensile tail which he uses as a fifth hand.  As he travels through the trees, he holds on to branches with his tail, freeing his hands (and feet) to pick fruit.  Any monkey that suffers a mutation that makes his tail less effective has a greater chance of falling and hence of not passing on his genes to the next generation.  This constant removal of monkeys with less effective tails highlights one of the characteristics of evolution.  Once an animal or plant is pretty well adapted to its environment, natural selection has far more to do with keeping animals (and plants) the same  than it has  to do with producing new species.

Now let's suppose that some of these monkeys start to move out on to the nearby plains to use a previous unutilized source of food.  They no longer need a prehensile tail.  Monkeys with less effective tails are no longer selected against and all sorts of tail mutations can be retained in the population.  Let's suppose that a tail is even a disadvantage.  At the very least, it takes resources to make a large specialized tail so perhaps that would tip the balance in favour of monkeys without tails*.  Here something interesting can happen.

*This assumes that the tail is not co-opted by evolution**  into some new function.  If so, natural selection will fit it closer and closer to whatever function it is now being used for. 

**Sorry for the anthropomorphism but you know what I mean.

Genetic sequences to produce some characteristic have actuator genes at the start of the sequence.  They turn the sequence on and off.  You can see this in your development.  You aren't born able to father (or mother) children.  The genes to do this are actuated at puberty. See this neat link.

If one of these actuator genes is mutated in the forest monkeys in such a way that the animal has no tail, that monkey is at a great disadvantage but in our hypothetical  monkey, by contrast, who lives on the savanna,  no tail is an advantage.  Having the actuator gene turned off imparts an advantage and leads to this characteristic being fixed in the plains living monkeys.

Even though the actuator gene is turned off, the gene sequence is still extant.    Without the pressure of a constant selection against animals with less effective tails that was occurring in the jungle, this dormant sequence can slowly degenerate.  Most mutations are harmful and the sequence for a tail will slowly be mutated and degraded.  It is a very slow process.  Occasionally an animal will be born in which the starter gene is turned on and this animal will have a tail.  The longer the time since the actuator was  turned off, the more degenerate the tail will be.  In fact, even though we humans are multi-millions of years away from the last of our ancestors that had a tail, very occasionally a human is born with a vestigial tail.  How does this all relate to a rapid radiation of new species, that I mentioned,  to fill empty ecological nitches.

Suppose now that man has hunted all the jungle monkeys with prehensile tails for their beautiful skins.  This nitch is empty and there are monkeys close by on the plains that occasionally have a "throw back" to a monkey with a tail.  If too much time has not gone by, and the tail is still effective, such a monkey finds that he is much more adept in the trees than his fellow monkeys and he no longer has competition from the much more tree-adapted jungle monkeys since man has wiped them out.  That nitch fills up again and natural selection once again selects for more and more effective tails*.

This process of starting up a disabled genetic code is sometimes called atavism activation and also works in the opposite sense.  For instance, in the ontogony (embryonic development) of a chicken (and presumably other birds) a "dinosaur" tail starts to develop.  Then another sequence actuates which re-absorbs the tail.  Evolution works in wierd and wonderful ways.  If you could turn off this tail absorbing sequence, a chicken would be hatched with a a tail.  To go into all the inns and outs of the way you could produce new species from the genetic material hidden in the present species would get very messy.  This is just a hint. Incidentally, the same sort of thing occurs in the "hand" of a bird with the fusion of the distal bones.  Turn this one off and a chicken will have an "arm" much like a dinosaur.  Also, teeth begin to develop and are absorbed before a chicken hatches.  Turn off these three genes and  Presto "dynochicken".

Of course this all depends on the fact that we didn't hunt all the plains monkeys to extinction as well.  The more populations that exist, the more possibilities there are for rapid radiation of species to fill empty nitches.  Otherwise, evolution has to start from scratch again.

This site gives some amusing  speculations about what might evolve

However, even if we were to eliminate everything except single celled organisms, evolution would once more populate the earth.  It would just take far longer and the results would likely be less recongnizable than if more familiar animals were still alive to radiate into the emptyness.

For that matter, we would be very unlikely to eliminate all humans.  We are like cockroaches.  Very hard to kill.  Our present civilization would become the stuff of legends with these fabulous beings (us) having supernatural characteristics.  Humans of the future would have all sorts of inventive explanations for what uses the artifacts they found were used for. I'd love to be a fly on the wall and hear how they explained, for instance, those little plastic bits that we use to close the bread bag.  If it didn't fall so close to home it would be rather fascinating to see us eliminate ourselves as a species. 

Destroying the Earth
When I talk about destroying the earth, I am talking about the biosphere and taking it back to an environment with only single celled organisms extant.  There is a way and we are pushing the system in that direction.  However even our awesome ability to destroy would be hard pushed to cause this much destruction.  Let me relate a little story first.

In a previous life I worked for a research outfit and we did some work for the Tsawassen ferry.  The Ferry takes off from Tsawassen which is located on the BC coast near the American border.  The bottom shelves off very gradually so they had to construct a causeway of fill to get into deep enough water for the Ferries to dock.  They found that seaweed was collecting in the angle between the beach and the causeway on one side and this thick collection of organic material began to rot.  It was thick enough to be anaerobic and one of the break down products of anaerobic decay is Hydrogen Sulphide.  Besides being smelly, and in fairly low concentrations, lethal, it was turning the nearby houses black.  In those days, the white pigment in paint was white lead and when Hydrogen sulphide reacts with Lead oxide it makes lead sulphide which is black.  We sorted out the problem but that is another story.

It has been suggested that previous extinction events, the production of Hydrogen sulphide from the oceans was a contributing factor.  Let's look at the most widely known extinction; the one that wiped out the dinosaurs.  Apparently a large chunk of rock slammed into the Yukitan peninsula and disrupted a layer of gypsum.  Gypsum is Calcium Sulphate and the extreme heating that occured would have produced acids of sulphur.  The total effect was a shading of the world, perhaps for a few years, and a sharp decrease in photosynthesis.

With photosynthesis largely shut down, the only oxygen entering the oceans would have been by diffusion and many of the oceans probably became deficient in oxygen and even anaerobic.  All the life in any part of the ocean that was depleated of oxygen would have died, rotted and produced Hydrogen Sulphide.  The food chain would have been totally disrupted since it depends on the growth of phytoplankton.    Hydrogen sulphide is highly toxic and would have contributed to the woes of the animal life on the land and in the seas.

At present, we have destroyed many of the fisheries of the world and are turning the oceans into jelly fish cultures.  Places where polluted rivers flow into the sea have huge blooms of algae which die periodically and turn the water dead*.  We are acidifying and warming the ocean.  It is conceivable that we could start a chain reaction by killing enough of the ocean that it depleats the oxygen in other areas which generate hydrogen sulphide and kill even more etc. 

* These areas are not actually dead.  They still grow anaerobic bacteria but to us oxygen breathers this is a close to death as it gets.

It would be so easy to reverse all this but we seem as stupid as a species as we are intelligent as individuals.  Sad.