Botanical Sexism Cultivates Home-Grown Allergies | Hacker News Reader

Botanical Sexism Cultivates Home-Grown Allergies

blogs.scientificamerican.com

68 pointsLanceTaylor34 comments

The only reason why we don't plant tons of edible fruit trees in city parks is because they would make a huge mess and attract rodents. But now that we're going to have self-driving robots that can clean up after the trees by the time they're old enough to produce fruit, there really isn't any reason why our park trees shouldn't be producing food for us.

The local parks I where I lived in Germany had apple and plum trees. In spite of the fact that all the fruit came in a short time in autumn, I never saw a fully ripe fruit on the trees, let alone a rotten one fall.

Between people and birds, there was nothing left for the rats.

> ...there really isn't any reason why our park trees shouldn't be producing food for us.

The article does address that notion -- trees are really good at capturing pollution, and a good amount of that pollution ends up in their fruit. Which sucks. I grew up foraging urban food, and I'll still pick and eat berries and stonefruits because they're too delicious to pass up, but it seems irresponsible for governments to promote such a thing.

> The article does address that notion -- trees are really good at capturing pollution, and a good amount of that pollution ends up in their fruit.

Right, you wouldn't be able to do this with street trees for that reason, but park trees are fine. The soil just needs to be tested on a regular basis for heavy metals, but that isn't especially difficult; e.g. this has already been done for a lot of community gardens in NYC. While fruit definitely contains whatever pollution is in the environment, unlike many mushrooms it generally doesn't hyper concentrate it.

> trees are really good at capturing pollution, and a good amount of that pollution ends up in their fruit

Must admit that this is a good reason against.

For what it's worth, this is quite literally a textbook example of the tragedy of the commons. Fruit will always be picked unripe, for if it is left to ripen, whoever chooses to leave it will have none.

As long as there are is enforcement to prevent people from harvesting stuff to sell, there would always be more food than people. E.g. in NYC there are something like 30,000 acres of parks, so you could have literally hundreds of acres landscaped with edible species without meaningfully reducing other forms of public space.

> because they would make a huge mess and attract rodents

So what? more for cats. This is just a cultural excuse. We don't need to do what is more easy or convenient for the gardener or every public space would be under a layer of green concrete now.

> there really isn't any reason why our park trees shouldn't be producing food for us.

exact

This is such an interesting insight into how urban planning decisions can affect health.

What are the chances that airborne allergens increase rates of food allergies?

As I understand it, very small.

Most allergens are denatured by acid and enzymes in the stomach. Many food allergies, which typically are not the same kind of immunological reaction as seasonal allergies/allergic rhinitis, are caused more by the failure of epidermal barriers or acid attack than by mere exposure. don't become sensitized because you ate something so much as because your body allowed bits to get somewhere they are not allowed to be under any circumstances, which is why the outsized anaphylactic reaction food allergies often cause.

(...typically. In some cases it is cross reaction, where an antigen in food is too similar to some other antigen the body has previously identified as an invader. See for example the temporary meat allergy that can be caused by some Lone Star tick bites. And there are yet other causes of course...)

Seasonal allergies are usually mild because they are generally localized, peripheral, and provoked in tissues that are designed to give this response as a normal protective action.

(That is, your nose is correct to run or stuff in response to histamine release caused by pollen. Frankly, I feel some foreboding about what sequelae we will eventually discover to be caused by chronic H2 antagonist administration over decades, drugs like Claritin/Zyrtec that people are taking every day of their lives.)

So! While it is possible and some rare cross reactions have been observed (particularly in fruiting trees/eating fruits), as a general rule your seasonal allergies do not increase your food allergy risk.

Now, some people are at higher risk for both due to environmental or genetic circumstances. But there it is a prior immune dysfunction that caused both rather than one causing the other-- though it's an understandable intuition to connect them as your question does. Having one or the other makes it more likely you have both, but it one doesn't cause the other.

>So! While it is possible and some rare cross reactions have been observed (particularly in fruiting trees/eating fruits), as a general rule your seasonal allergies do not increase your food allergy risk.

If you're talking about oral allergy syndrome, it isn't really what I'd call rare.

If by "batonical sexism" we mean the choice to use male trees instead of female trees because it'd be a burden to clean up parts of the female tree that drop to the ground seasonally. It's a straightforward tradeoff: use male trees that produce pollen (and make it worse for allergies) or use female trees that have to get cleaned up (or plant both, and deal with both problems).

As the article notes, planting both actually reduces one of the problems: pollen. Female plants attract and capture pollen. So you will slightly increase litter while moderately reducing pollen.

Additionally, as the article also notes, all allergens are not created equal. Pollen is mostly notable insofar as it is allergenic; planting trees with low or nor allergenic pollen uncouples "pollen" and "pollen that causes allergies" levels.

> So you will slightly increase litter while moderately reducing pollen.

I don't see any indication that the increase in litter would at all be of greater proportion than the decrease in pollen. Only that bit of pollen that gets blown to a neighboring female tree would get absorbed. Not even all of that, since presumably the majority would get blown off the tree. I can't see how any more than a single digit percent of the pollen would be captured, so people with allergies would still be affected.

The increase in litter would be significant if half the trees were female. On my college campus there were parts of the year where certain types of trees would drop seed pods and it littered the streets for the better part of a week. It'd take a significant amount of manpower to clean it up - probably a garbage-bag per tree - so we just left it outside and dealt with vegetation litter for a couple weeks.

Unless the article backs up the claim that the pollen reduction would be substantial and the increase in litter trivial it could still very well be that a mix of female and male plants does not prevent allergic reactions to such a degree that it's worth using a mix of plants.

tl;dr

Male trees were planted disproportionate to female trees in urban settings because they didn't shed messy seeds. The preponderance of male trees increases the amount of pollen exposure. Author asserts this leads to an epidemic of allergies/asthma. Author asserts this indirectly leads to cancer.

Author fails to apparently take into account that although we are exposed to more male trees than female trees, our total tree (and therefore, pollen) exposure is far lower than historic norms. If adverse consequences are due to pollen over-exposure, we would still be net underexposed to pollen, so any increase in adverse health consequences couldn't be explained by that.

Author also presents themselves as a "horticultural epidemiologist." Worth noting that a google scholar search suggests this person is not an academic and holds no academic credentials, but he does make his income flogging a pair of books on this topic. I guess "Epidemiologist" isn't a protected title, but I usually don't see it applied to someone that doesn't actually work in epidemiology, or hold a degree in epidemiology.

One thing that isn't clear is how effective female trees are at removing pollen from the air. Is it possible that even with a much higher population but a more balanced sex ratio, there would still be a lower airborne pollen count?

Yes, that's the core premise made by the author: If we're going to plant male plants, either we plant female plants (which have evolved to take up the maximum amount of pollen possible) or our lungs take up the pollen (which results in biological issues).

There's an inflection point where the amount of pollen left in the air by a sparse male forest equals the amount of pollen left in the air by a dense balanced-ratio forest. The article doesn't say where that inflection point is, though — when you state that inflection point as "a balanced-ratio forest can be XYZ as dense as a male-only forest with same or lower pollen counts", XYZ could be 1.1x, 20x, 5000x. Extrapolating that to urban trees, with pollen measured at human face heights, would be the holy grail of prove-or-disprove the value of this approach.

It is very likely that trees evolved to pollinate no more than is necessary to deliver the correct amount of pollen to the trees near them. I cannot find any estimates of this percentage at all, so as with XYZ above, it could be 1%, 10%, or 99%. More science is definitely required in both forest-shaped configurations and urban-shaped pockets.

I wonder how good trees really are at attracting pollen. Intuitively it sounds like the forces should be small and the effect should be pretty marginal.

Trees are 0.3 billion years old, so presumably they are not just good at it, but best at it.

And birds are about 160 million years old, but they can't fly as high or as fast as airplanes. Evolution doesn't plan ahead, so it easily gets stuck in local maxima.

Birds seem to fall out of the sky a lot less often. Could be the same is true for pollen. I don’t know if I agree with the guy, but I think he’s right to encourage more science time and money spent on it.

What? How could you think this is remotely true. It's international news when a commercial aircraft crashes. Birds, not so much.

Observer fallacy, though I’m kind of confused why I’ve never personally seen it happen. I’ve seem one window strike but never a ground strike.

If you want to observe birds there are some great nest cams all over the world.

The first days/weeks/months of flying is not perfect. A large predatory bird needs a lot of training and exercise. Wildlife rehabilitation is an other good source to hear about the work involved in getting wild birds to fly.

I don't know about that. A good number of them end up dead below my windows each year.

Pollen is cheap and male trees overproduce it to get an edge over other male trees. Most polen just fall to the floor, a tiny part is lucky and reach the flowers in the female trees.

That's why many plants have nice flowers and use the help of insect to transport the pollen from a plant to another plant. (By the way, the yellow balls in the legs of the bees are pollen that they collect and take to the hive, for food. They "stole" most of the pollen, a small part drops in the other flower.)

Also, the link in the article in the sentence "The pollen grains do not just get to the female trees by accident; rather they are drawn there by this mutual attraction." is not a good justification of that "fact".

Would it be feasible to genetically engineer trees to neither drop seeds nor release airborne pollen?

You don’t have to genetically engineer it. Just clone (known for millennia) a barren plant.

Great article, horrible title

You ever see one of those titles where individually you know all the words, but don't know what they mean together?

The 10 people who died from the pollen storm in Melbourne was interesting.

https://www.google.com.au/amp/amp.abc.net.au/article/9907120

It also interesting because it possibly only showed up because it hit the media, but it should have been see-able before if proper stats were kept over the long term.

To use male trees in parks (when possible) is a technical choice, totally unrelated with sexism. To link all things with female opression is unhealthy and a mess leading to absurd dead ends.

Cities are full of "male symbols" in form of phallic shaped towers and square high buildings. Should we remove all of them and start building round hemispheric houses instead? Should we remove only the 50% of skyscrapers?

The term botanical sexism is unfair for garden designers (not always men) and creates a non-existent problem

I think you missed the point of the article.

Maybe the writer should have used a better title then. Less clickbaity and annoying. That some pollens can trigger allergies when combined with diesel particles is not exactly breaking news.

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