Adaptation to Seasons: The Evolutionary Explanation

[jimmy1200]

what does evolution say about why we have seasons. is evolution the proper term to use here? well anyways, for what reason would seasons rise out of chaos. it seems rather that they would be created to play out the game of life, not for any true purpose. i mean there is a purpose now, but why would we need seasons. is this a philosophy topic?

 

[Andre]

what does evolution say about why we have seasons.

Evolution says nothing. Evolution is all about adaptation. Seasons are there just because of the physical properties of the Earth rotation axis being at an oblique angle to the orbit around the sun.

There is neither a purpose in nature nor a purpose of nature. The only purpose of life is to sustain life itselves. That's what makes nature so complicated.

 

[SEG9585]

I would think we need seasons so that the majority of the planet gets an even distribution of light and heat. An untilted axis would result in unbearable temperatures at the equator and much less comfortable temperatures everywhere north and south of the tropic of cancer and tropic of capricorn lines. It likely also plays a heavy role in weather (water distribution). So yes, seasons are very necessary

 

[matthyaouw]

Currently, people need seasons due to the variations in climate and rainfall that they produce, for example in the tropical wet-dry climate that exists around the tropics. If the Inbter Tropical Convergence zone were to stop its seasonal migration, and seasonal rainfall were to cease in the african savanna, the drought and famine it would bring would wipe out many. Do we need seasons however? If seasons had never existed, any species on the planet would not have adapted to live in a seasonal climate, and so no we would not need seasons. Even if the Earth's seasons were to cease, we would most probably adapt to the new climate, as many species have done in the past, so ultimatey I'd say seasons are useful, but not nessecary.

 

[JAR]

I agree with andre to an extent. It is true that seasons are no result of evolution at all. But the idea if we need them or not is questionable. Seasons do circulate the energy around the planet allowing for a better distribution. But had there been no tilt in the first place would life still been able to form? That is hard to answer since we do not know why life can just suddenly form.
I would say as of right now we do need seasons because that is what we have adapted to or evolved to need. If seasons were to cease our species would certainly be affected. But nature would adapt.

 

[theriddler876]

blah we don't need seasons in fact near the equator there are no seasons, and man evolved in africa where there are no seasons, as in spring winter and fall and such, but rather a rainy one and a non rainy one, and it was this that a warm shelter was not required which is good

 

[shrumeo]

Agreed, life does not require seasons but adapts to it where there are seasons, as in anywhere but the tropics.

 

[Seafang]

I would think we need seasons so that the majority of the planet gets an even distribution of light and heat. An untilted axis would result in unbearable temperatures at the equator and much less comfortable temperatures everywhere north and south of the tropic of cancer and tropic of capricorn lines. It likely also plays a heavy role in weather (water distribution). So yes, seasons are very necessary

Well the hottest temperatures recorded in the summer northern deserts of Arabia and Africa are around +135F (air temperature) and much hotter than that for ground temperatures, while the coldest are recorded simultaneously in the middle of the antarctic winter night, around -125F. That is a pretty extreme range already. I don't see any reason why it would be very much different in the absence of an axis tilt and seasons.

Life evolved to take advantage of seasons for survival strategies, but in no way are seasons necessary. the Earth with its oceans is perfectly capable of regulating its temperatures as it does now by controlling evaporation and cloud cover.

Get rid of the axis tilt and all that would happen is that the cloud cover would change to regulate the temperature.

 

[ray b]

I like the sub-tropics
here in miami we have two seasons
hot and sometime a little cool rarely cold

you guys in the snow belt are nuts

 

[Sanaro]

jimmy,

There are three reasons why we have seasons:

The first reason involves Kepler's Law (of orbital mechanics). The Earth's orbit around the Sun is an elipse, not a circle. We don't remain at a constant distance from the Sun during the year. The distance varies from about 91,500,000 miles to 94,500,000 miles.

Second, the Earth's rotational axis is tilted relative to the plane of the ecliptic. The north pole is currently inclined 23.5 degrees away from the Sun.

Third, the Earth's orbit around the Sun is inclined relative to the plane of the ecliptic. The orbit doesn't lay directly in the plane of the Sun's equator. For six months the Earth is "above" the plane and for six months it is "below" the plane.

These three reasons not only explan why we have seasons but they also explain why the southern hemisphere has more extreme seasonal weather than the northern hemisphere.

The northern hemisphere is tilted away from he Sun. It is winter in the north when the Earth is closest to the Sun and this also coincides with the Earth being at the highest point above the plane. The northern hemisphere is exposed to less direct light and has its shortest days, but the winter isn't extreme because the Sun is at its closest point. Simultaneously it is summer in the southern hemisphere. The south receives more direct sunlight and the Earth is at it's closest approach to the Sun. The summer is very hot there.

Six months later the situation reverses. When the Earth is below the plane the north gets its most direct exposure to sunlight. But the Earth is at its farthest distance from the Sun. The summer isn't as extreme as in the south. Simultaneously, in the south, it is winter. The south is receiving the least direct sunlight, the days are the shortest and the Earth is as far from the Sun as it gets. This results in harsh winters. This is why the Antarctic weather is more extreme than the Arctic weather.

 

[hitssquad]

The evolutionary adaptiveness of seasonality

Evolution says nothing.

Perhaps you are not listening hard enough. Natural selection seems to have said that seasonality is adaptive in this particular time and place.

 

[hitssquad]

The northern hemisphere ... tilted away from the Sun coincides with the Earth being at the highest point above the plane.

No. The plain of the ecliptic and the tilt of the Earth are two aspects of the same thing, not two separate things that can have coincidental respective aspects.

 

[Andre]

All close but this page may explain the pecularities of seasons, solstices, equinoxes aphelion and perihelion the best.

Evolution says nothing... and
Natural selection seems to have said that seasonality is adaptive in this particular time and place.

are not mutually exclusive. This is more philosophical. It's not that evolution has a purpose to be reached. Evolution is obiviously about survival, about reactions and adaptations to the changing environment.

 

[SEG9585]

Sanaro--
He was asking whether or not seasons are necessary for life, not why seasons occur..

 

[theriddler876]

no seasons are not necessary for life.

 

[JonahHex]

Remember, there is a big difference between "life" and "life, as we know it." The relatively recent discovery of life around the deep-sea fumerols is an example of some serious change in "as we know it."

Even this long after Galeleo, questions like this still demonstrate our very strong human-centric view of the universe. The Earth got along fine without us, and even without life, for several billion years, and if we were to all disappear today, it would continue to get along just fine.

With seasons, without seasons. Big deal. Life either adapts to the presence or absence of them, or not. If not, oh well. This is what evolution says about them.

 

[JANY]

are seasons there so that life can die out and renew in another form or just refresh..nothing lives forever..are the seasons the reason for this..theres a time for everything in its place...

 

[Astronuc]

The seasons are a consequence of the Earth's 'tilt', rotation and revolution about the sun.

As Andre points outs in post #2, life adapted to the daily and annual cycles. Life spans of years can last many seasons.

Life is based on (bio)chemical processes, and that has more to do with the life span than annual cycles.

 

[HallsofIvy]

are seasons there so that life can die out and renew in another form or just refresh..nothing lives forever..are the seasons the reason for this..theres a time for everything in its place...

Then why do large parts of the earth, the tropics, and, indeed, the parts where life is most rife, have little or no seasons?

 

[Phrak]

In summation,

1) There is a collective "we" that either needs seasons, or does not.
2) Life doesn't have a purpose, and this means the purpose of life is life.
3) There's a thing called natural selection that can talk.

How's that?

 

[cripto88]

Evolution says nothing. Evolution is all about adaptation. Seasons are there just because of the physical properties of the Earth rotation axis being at an oblique angle to the orbit around the sun.

There is neither a purpose in nature nor a purpose of nature. The only purpose of life is to sustain life itselves. That's what makes nature so complicated.

Life no more has a purpose than the seasons in the sense of evolution.
No more purpose than a lump of granite. It's just there because it is there.

 

[jim mcnamara]

Then why do large parts of the earth, the tropics, and, indeed, the parts where life is most rife, have little or no seasons?

The tropics experience minor "seasons", just not those we see in the temperate zones. Unless you are in montane areas where adiabatic cooling creates almost daily rain - like in a cloud forest - there are large areas between the Tropic of Cancer and the Tropic of Capricorn with dry seasons and wet seasons. During the wet season there are monsoonal rains, during the dry season there may be sporadic rainfall, but more often there is none.

The reason for this is that insolation - solar input due to the angle of the sun - does not vary that much over the year. So temperatures tend to stay in a fixed zone. Plus the jet streams that move arctic air out of polar regions, seldom affect equatorial regions. They are "insulated" from the cold so to speak.

 

[mgb_phys]

I like the sub-tropics
here in miami we have two seasons
hot and sometime a little cool rarely cold

I used to live in LA where there were two seasons.
Hot and Hot with holiday decorations!
I now live in Canada where there is - Winter and Road repair

 

[LURCH]

To put it another way; life as we know it requires seasons because the seasons were there first, and life adapted to work in harmony with them. That is, most Earth life is designed to take whatever advantage can be gained from the repetitive pattern of the seasons, and avoid whatever detriment these constant changes could involve. If the Earth had different seasons, or no seasons, then life could still exist. But such life would be quite different from the life forms that do exist.