Does the size of the human population mean that evolution has stopped?

Question

There is now no way for a beneficial mutation to spread throughout the entire population of the planet, therefore there can be no more meaningful evolution of the human race. Alternatively, is it possible given a few more million years for several distinct human species to evolve. Presumably this would have happened if groups on different continents had remained separated.

1. Evolution has 2 elements, random mutation and environmental selection. The mutations will continue to happen until we can work out a way to completely control our genes, the selection may not be as natural as in the past, but must still occur (unless women choose their partners completely at random). For a species to evolve, the mutated genes must replace the entire population, which is what I really meant by meaningful evolution - I'm familiar with Dr Dawkins work and know there's no 'plan'.

2. Evolution is not a theory that has been dreamed up on a whim, it is a scientific theory that has been created to fit the known facts. There is plenty of evidence for it, and no other explanation that plausibly explains what we see around us.

3. Humans have hardly changed in 50,000 years, and the first individuals recognised as human are around 2 million years old.

Anyway, looks like the points are going to Leanne, proving I have no morals ;-)

Answer 1

i think that there are already several distinct human species, these are...the gormless, the intelligent, the angry, the selfish, the beautiful and the ugly!

i am a cross between beautiful and intelligent!

Answer 2

I honestly think that humans have stopped evolving (in a sense of bettering the population). We are still changing, yes. People are taller on average than in the 1800s etc, but all useful mutations are stopped. Think about it: in the beginnings of the human race, the intelligent and strong survived. The weak died. I have poor eyesight, I would have probably died a couple years ago from not being able to find food or watch for predators. I have a good immune system, but the people now who have to be on drugs constantly for allergies or whatever else? Dead. Any major disease- Dead.
Killing the weak off early kept the disease and less advantagous genes down. Now people are living with things that would have killed them off, have we not improved health care to keep people living as long as possible. Now, for example, someone with severe allergies or multiple genetic defects can have kids- passing on the bad genes.

There will never be distinct human species- the world has interbred it's gene pool. It was started before humans started travelling (note the different colors of race and cultures). Now, people from different races are interbreeding, mixing up the gene pool.

Plus, with the way the human race is destroying earth, I honestly do not think that we will live another couple million years. The dinosaurs (kings of the land) were killed off presumably by an asteroid, or a drought. Humans I believe will be their own destruction.

Answer 3

I believe that different species have already started to evolve. I saw a guy today at university who had two thumbs- both with a nail. One was dangling of the other! I'm serious.

On a serious note I believe that although it may be possible for humans to evolve in the future, I do not believe our planet will be around in a few millions years to see that evolution happen. Our planet will either slowly die at the hands of the human race due to things such as global warming etc. or be destroyed by a freak catastrophe such as an asteroid or comet.

Answer 4

First, the human population continues to grow, there's a statistic that says 24 babies around the world are born every 10 seconds.

Second, the human specie is still quite young, about 10,000 years old, and evolution is a very slow process, it's happening as we speak but we could hardly notice it.

Genetic engineering perhaps would speed this up or take control of our human evolution completely.

Answer 5

Firstly you are assuming that Evolution is a fact. Now I am not a Christian and do not favour any other explanation for how we came to be here but the truth remains that Evolution is a THEORY which may or may not prove to be accurate. I completely accept evolution on a micro level but even on this level show me the hard evidence. Medieval skeletons always have much bigger jawbones because they chewed much tougher food and now we are getting more flimsy (in the UK at least). Surely that must be more devolution than evolution. Can't see how a new species is going to evolve - hasn't done so far so why should it start now.

Answer 6

The "beneficial mutation" is probably already there in the population. The size and diversity of the human population means that there are likely to be many mutations which may permit the survival of some individuals and not others.

As an examples:-

a small group of people have been found to be naturally immune to AIDS. Research has shown that the most likely cause is that they inherited the immunity from ancestors who caught - and survived - the Plague in the Middle Ages.

The projected bird flu pandemic if it happens will separate those who are resistant enough to survive from those who are not. It seems from studies on the 1918 flu pandemic that the most vulnerable age group are those in young adulthood because their immune systems "over-react". This age group is the one most likely to be producing children so the removal of adults of child-producing age with over active immune systems may represent a small but significant evolutionary change in the population.

Global warming and increased solar radiation will mean that pale-skinned individuals may be more susceptible to skin cancer and heat exhaustion than darker-skinned people... over time this may result in an average darkening of human skin.

Humans have changed immensely in the last 50,000 years... for example...
just a few hundred years ago anyone over 6 feet tall was considered a giant but now there's enough in even the smallest town to form a basketball team.

There are many more people alive today with poor eyesight than there ever were before because we have spectacles and contact lenses to deal with it. 50,000 years ago these people would have been a liability and easy prey.

The average human lifespan has increased from around 20-30 to 70+

The average birth weight of human babies, has greatly increased.

All these things have meant that the population of humans has changed and is continuing to change.

Answer 7

Has it stopped, well no.
The spread of disease and other environmental factors impact the micro-evolutionary change in humans.
For there to be a macro-evolutionary change, we usually see an event which gives rise to a 'punctuated equilibrium'.
This means that rapid change into new differing species usually happens rapidly and as the result of a catastrophe.
So the poster above that said an asteroid, is correct. That said, other environmental causes can affect the process.

Answer 8

No. evolution is a very slow process, which can not be counted by couple of years., but in millions of years. Population is only number indicating " how many are there" and nothing to do with evolution.

Answer 9

Speciation or seperated population adapting to their own particular environment and diverge eventually resulting in distinct human species is unlikely as because of globalisation. As the world is becoming a global village, our lives are being integrated and thus it is unlikely that we reproduce allopatrically.

Answer 10

Evolution hasn't stopped. Please stop thinking evolution is "meaningful". It is not. It is simply things that happen that make some individuals able to reproduce more offspring than some other individuals.