IMHO there never has been a need for humans. Perhaps no species are needed. However, some species make an environment that other species can thrive in. Anerobic bacteria that emitted oxygen as a waste product made it possible for oxygen breathing life to evolve even though they limited their own environment since high levels of oxygen are toxic for anerobic bacteria. Lichen which break down rocks help in soil creation which makes life possible for both plants and the animals that feed on them. Humans are the only species that has caused a mass extinction of other species. Cockroaches, rats, sparrows and domestic animals have thrived along with humanity. Most other species have not. The sooner we become extinct the better off most other life forms will be.

Of course I was looking at matters from the viewpoint of non-human species. I like being here. However, no species can increase indefinitely. At some point their numbers exceeds the carrying capacity of the environment. Our species may have already passed that point although it may not become evident for a while.

It may take considerable time for the planet to recover when we become extinct. However, we can delay our extinction and the extinction of other species by taking rational steps to limit our numbers and preserve habitat.

davidf

you and Bob Brown seem of similar alien religion.

david..i find it interesting[curious]..
you began the tale with oxigen

life has its beginings long before that
[think life like them sulfer vents..life forms..under sea's]

and about the high acidity..
sulpher etc that melted rock..broke up dust..so other life forms [moulds etc could 'do their thing'

im presuming you need o..before making co2?

but im fine skipping life true beginnings..[in the deep*]

but yes huhmans are needed
cause machines couldnt re-ply back.. to you

but them again..we wouldnt know it it did
but even if not machines..life needs us..to tell its full story

bacteria only record their bit of it
but we can join the dots

we are that pinacle of life..[trhe ONLY life that can make sense of symbols[writing..plus write back]

this special gift allows us to read the most inner thoughts
those long dead put into word..we will rise abouve the beast[our brother]by serving them...peace/love logic too

what they teach us
about our own creator
is what they give..what of us giving back?

we collectivly are as close to being gods
as beasts are ever likely to get

Ah!...the familiar thud of runner hurling needless abuse.

Fascinating really, an embarrassment to his creed.

Well David F, if you look at the history of earth over the billions
of years, humans have only been here in the relative blink of an
eyelid.

Its really all about being a planet of bacteria and viruses and
they will continue to dominate, with or without mammals.

Long term, biodiversity will dominate, as when one species crowds
together, apart from stretching resources to the limit, the species
barrier is broken, making it so much easier for mutating viruses
to spread.

So if Runner, Cheryl and others are so ignorant as to think that
they are their progeny can ignore nature and crowd together cheek
to cheek with impunity, let them learn the hard way. One mutating
virus will be all that it needs.

Clearly our species has evolved to invent interesting new things,
but those who ignore the laws of nature will sadly most likely
also cause its demise through sheer ignorance. So be it.

yabby has it about right, we are well on the way to testing the matter.
It is a shame about runner, but maybe he is not able to do other.