Stupid Science Questions Thread

[Ensign Steve]

Originally Posted by Dingfod

None at all?

Obvious bleach job.

[The Lone Ranger]

There are at least 4 different sets of genes that determine hair color, and there are at least 2 different sets of genes that determine eye color. They do not appear to be linked, however, so it is entirely possible for a natural blond(e) to have brown eyes.


Ancestral humans (who lived near the equator) were almost-certainly dark-skinned, dark-haired, and dark-eyed. All of these adaptations help protect against the damaging effects of ultraviolet radiation.

As people moved north, away from the equator, it became advantageous to evolve lighter skin. That's because we absorb solar radiation and use that captured energy to produce vitamin D (the "sunshine vitamin"). In northern climates, where sunlight is less intense, dark-skinned people often suffer from vitamin D deficiency. (This is one reason why it's added to milk.)



So it's thought that lighter skin evolved in people of northern climates as an adaptation to the relatively low availability of sunlight.

Blond hair and blue eyes are a different matter: no one is quite sure what (if any) advantage they are. It may be that some of the same genetic mutations that caused decreased melanin production in the skin (thus leading to lighter skin) also led to decreased melanin production in the irises of the eyes (and thus, blue eyes) and in the hair follicles (leading to blond hair). If that's the case, then blond(e) hair and blue eyes are more or less accidental byproducts of genetic mutations that led to lighter skin.


They may be adaptive, however. Because the irises of a blue-eyed person absorb less light than do those of a brown- or black-eyed person, more light reaches the photosensitive cells of the retina in a blue-eyed person. So there's some speculation that blue eyes might be adaptive in that they permit better vision in low-light conditions than do dark eyes. (On the other hand, a dark-eyed person's eyes are better protected against damage from ultraviolet radiation.)


Blond(e) hair is even more of a mystery. If it's an adaptive trait, it's not at all clear how. A common explanation is that it is a result of sexual selection -- that in some populations, blond-haired mates were preferred over darker-haired mates.


As an aside, mutations causing blond(e) hair have arisen multiple times in human history. For instance, some Australian Aborigines are blond. It seems a good bet that they didn't inherit the genes for blond hair from Northern Europeans.



Anyway, the long and short of it is that mutations for both blond hair and blue eyes arose in Northern European populations, and have persisted -- whether by chance, because such traits were considered "sexy," or because these traits were adaptive in that environment. But the traits aren't directly linked, so it's entirely possible to have blond(e) hair and brown eyes.


Surely, these mutations have occurred in more southern climes from time to time, but each of them is likely to be disadvantageous in an equatorial climate.

A light-skinned person in a sunny equatorial region has a much higher probability of dying from skin cancer than does a dark-skinned person.

In sunnier regions, dark eyes seem to provide better protection against damage to the retina from ultraviolet radiation. (Ironically, though, dark-eyed people seem to be more vulnerable to cataracts than are light-eyed people; presumably, this is because darker irises absorb more solar radiation than do lighter irises.) Darker eyes may also be advantageous in sunny climates because a dark-eyed person is less likely to be dazzled by the bright light than a light-eyed person.

Blond(e) hair may be disadvantageous in very sunny climates because it is less efficient at absorbing incoming sunlight than is dark hair. This means that more sunlight (including dangerous ultraviolet radiation) passes through the hair of a light-haired person and reaches the skin of the head, where it will be absorbed.


Cheers,

Michael

[erimir]

My mother has (light) brown eyes, and is a natural blonde.

[Ensign Steve]

Originally Posted by The Lone Ranger

A light-skinned person in a sunny equatorial region has a much higher probability of dying from skin cancer than does a dark-skinned person.

How likely are they to die before they breed, though? Isn't it the case that things that kill us in old age (heart disease, Huntington's, diabetes) are still prevalent because they get passed on to our offspring before they kill us?

[BDS]

Originally Posted by Ensign Steve

How likely are they to die before they breed, though? Isn't it the case that things that kill us in old age (heart disease, Huntington's, diabetes) are still prevalent because they get passed on to our offspring before they kill us?

I don't know the answer. However, grandparents probably have adaptive value to their grandchildren in almost all human societies. Inasmuch as grandparents share their resources with their adult children and with their grandchildren, inasmuch as they help teach and care for said children, it would be an adaptive disadvantage to the descendant-leaving-success of those grandparents to die relatively young, even if they died after their child-bearing years.

Of course it would not be AS significant a disadvantage as to die at age 25 or 30.

[The Lone Ranger]

Indeed. While most cancers take years to kill, skin cancers, in particular, often kill people during their reproductive years and so can have a direct effect on fitness.

But probably more importantly, it is indeed widely believed that the presence of grandparents has historically been an important factor in the successful raising of children. Not only because they can pass on wisdom and information (a vital factor in a species such as ours, in which success depends on knowing the best times and places to hunt for food, etc.), but because they can help to care for their grandkids.

In fact, it has been suggested that this may be part of the reason that women tend to live longer than men -- because there has been selective pressure for women (who generally invest more in the care of offspring than do men) to live longer, so that they can help care for their grandchildren.


Cheers,

Michael

[Qingdai]

There is one species that has the males live longer or as long as the females, and in that species the males also take care of off-spring.
I'd have to go back to OMSI to figure it out though.

[godfry n. glad]

Okay....Last weekend, during the heat spell, I went searching for a wedding gift. The specific gift I was tasked with finding was a galvanized steel watering can. It was on the happy couples' list at Target, but the spot on the shelves was empty....that's why the task was tossed to me, mister garden guy.

So...since I was touring the Tour de Coops and they had three...count 'em, three!...trendy inner city nurseries on the list. I thought I'd just pick one up along the way. No such luck. Not a single one had my the object I sought. At one of these trendy inner city nurseries, a staff member even threw her nose up in the air, sniffed, and stated that, "We don't carry them. They release residues into the soil. We have only plastic watering cans."

WTF?

"'Residues' into the soil?"

It's not like zinc oxide and iron oxide are particularly pernicious toxic residues....at least the last I heard. Am I missing something here?

Is there anything I really need to be concerned with my galvanized watering can? Is it slowing killing me and my family through the masses of oxidized zinc and steel it has released into the soil over the years I've owned it?

[The Lone Ranger]

There is a remarkably good correlation between parental investment and longevity.

For instance, there was a Caltech study of 10 different primate species in which the researchers correlated longevity of the two sexes with the amount of care that each sex invests in offspring.


In each species in which females are the primary caregivers, females outlive males, on average. This includes spider monkeys, gibbons, and orangutans. In each of these species, the female invests much more in childcare than does the male, and in each of these species, the female lives significantly longer than does the male, on average.

In gorillas, females are the primary caregivers, and females outlive males, on average. But the difference in longevity between males and females isn't as great in gorillas as in primate species such as orangutans, in which the female is the only caregiver. But male gorillas often play with, protect, and otherwise help care for their offspring. Similarly, the difference between male and female longevity in humans isn't as great as it is in most other primate species. But then, male humans generally take a much more active role in caring for their offspring than do most other male primates.

There are at least two different primate species in which the males are the primary care-givers, Owl Monkeys and Titi Monkeys. The Caltech study found that male Owl Monkeys live significantly longer, on average, than do females. (They found the same result for Titi Monkeys, but the sample size was too small to determine whether the effect was statistically significant.)


Cheers,

Michael

[The Lone Ranger]

Zinc is an essential element for both plants and animals, but in sufficient concentration, can be harmful or even toxic.

I doubt very much that there's going to be enough zinc released from a galvanized watering can to make any difference. Indeed, the lack of sufficient zinc in the soil is often a limiting factor in plant growth; using a galvanized watering can might actually improve plant growth to a slight extent.


That having been said, if galvanized steel is exposed to high heat (as in cooking) and/or an acid, potentially-dangerous amounts of zinc can be released. This is why galvanized steel containers are not used for storage of foods, especially acidic foods like tomatoes, unless they have an inner plastic lining to keep the food from ever coming into contact with the galvanized steel. There have been a number of cases of zinc poisoning that were apparently caused by the eating of acidic food that had been stored in unlined galvanized steel containers.

The Michigan State University Extension recommends that galvanized steel should never be used for preparing or storing of food. (That is, don't used galvanized steel for grills or cooking utensils, nor for storage bins.)


Cheers,

Michael

[godfry n. glad]

Right...

I'll pass it along to the happy couple not to prepare or store foodstuffs in their galvanized watering can, particularly acidic foods like tomatoes or Coca-Cola.

Thanks, Michael...My under my breath comment in the nursery was "yeah...residues like essential trace minerals in the soil." At least I know with the galvanized steel can that it will recognizably degrade within a human lifetime. With plastics, I'm not so sure.

[The Lone Ranger]

Yup. I wouldn't be at all surprised if the plants actually do a bit better if they're watered from a galvanized steel waterer.

And unless they're made from photodegradable plastic, thosed danged plastic containers are going to be around for a long time. (And most "photodegradable" plastics don't actually degrade into their component chemicals; they simply break down into smaller bits of non-biodegradable plastic.)

Cheers,

Michael

[Nullifidian]

Originally Posted by Dingfod

None at all?

None?

To add to the list, here's Catherine Deneuve in Belle du Jour:





Catherine Deneuve was my childhood crush. I was the only ten year-old I knew who liked films from the French New Wave.

[godfry n. glad]

That's understandable, Null.

She was right up there for me, too, along with Blythe Danner, Paula Prentiss and Ingrid Bergman. Okay....so I was fickle.

[Doctor X]

The best comment on Catherine comes from Susan Sarrandon . . . Sarr . . . Janet.

Apparently, the "Suits" wanted to stress that Susan's character was "drunk" in a scene in which Catherine seduces her and has a lesbian relationship.

show spoiler

To paraphrase: "Like you need alcohol to be seduced by Catherine Deneuve!"

--J.D.

[Angakuk]

Why does it always seem to rain right after all the farmers cut their hay and before they can get it baled?

I have my own theory. I think that all that hay drying raises the local humidity, thus overburdening the atmosphere with moisture and causing the clouds to dump their load. Whenever I voice this theory the college educated farmers all laugh at me. I hate it that they feel entitled to mock my theory just because they took some ag-science course 30 years ago. Don't they realize that rain follows the plow?

[Dingfod]

Say a Mars mission spacecraft was constructed in low earth orbit with a photon rocket engine attached capable of accelerating the craft by a relatively slow 0.001 G continuously for all the way to Mars. I've estimated the such a spacecraft would reach escape velocity from Earth's gravitational pull in less than 100 hours in an ever widening orbit as the speed increased, but I could be way off on that. On it goes toward Mars, which will be intercepted when it's fairly close, say 200 million kilometers. If the spacecraft continues to accelerate at 0.001 G for half the distance, turns around and decelerates to Mars orbital velocity, how long would it take to get there and what kind of speed to would be attained at the maximum? How much energy per kilogram would it take?

[Ensign Steve]

I don't think that's a stupid question.

[Dingfod]

It's stupid because that's the sort of shit I think about but am too lazy to figure out for myself because there's really no reason for me to need to know something like that, only I want to know. Why, I do not know.

[Jug Pilot]

From my son:

How far would you have to move the Earth from the Sun to reduce the temperature 10 degrees?

[naturalist.atheist]

Originally Posted by Jug Pilot

From my son:

How far would you have to move the Earth from the Sun to reduce the temperature 10 degrees?

As a rough guess r = re/sqr((ta - 10)/ta) ~ 1.05re : assuming 100F is ta.

This is only a rough estimate since the core of the earth is a net radiator and the earth does have a dynamic capacity to increase cloud cover to slow heat loss.

[Dingfod]

Originally Posted by Jug Pilot

From my son:

How far would you have to move the Earth from the Sun to reduce the temperature 10 degrees?

Ah, the plot to move the Earth that the Russians were dissing.

[naturalist.atheist]

Originally Posted by Dingfod

Ah, the plot to move the Earth that the Russians were dissing.

Maybe you have that confused with Bill Gates' plan to stop hurricanes.

[LadyShea]

Do lower order animals often show individuality?

We have large banana spiders (golden silk spiders) on either side of our porch entry, about 5 feet apart. They are about the same size, with the same sized webs, definitely same species, but they behave so differently with regards to feeding and web maintenance.

The clean one (called S for my mother) works on her web several times a day seemingly for maintenance, and repairs it anytime a bug, wind, rain, etc. wrecks it. The other day she was frantic as it rained all day and blew in leaves and such. I've never seen a spider work so hard. When she catches something she goes to where it is, wraps it up only enough to immobilize it, eats it right there, then cuts the carcass from her web and repairs the hole.

The other one (B for me ) never repairs holes, she just throws up more anchor lines. If she gets a bug, she goes to where it is, wraps it up really tight, hooks a towline to it, drags it to the top and hooks it there, eats it, then leaves the carcass...they are all lined up and some have been there over a month. The bottom of her web is littered with legs, wings, parts of her old self from molting, blown in debris, etc.

Seems weird to me that they can have personalities.

[Jug Pilot]

Thanks guys!

One more

On the discovery channel we were watching said the moon was twice as big in the sky when the dinosaurs were alive. How much higher/lower would high tide and low tide be?