Menstruation: What is the evolutionary or biological purpose of having periods? Why can’t women just get pregnant without the menstrual cycle?

This is a copy of a discussion on question/answer site Quora, which I heartily recommend that my followers go browse in – you’ll rapidly find yourself falling down a rabbit hole of time-sink, all contributed to by the fact that most answers are made by people who are actually experts in the stuff they’re talking about. In particular this is one person’s answer to the titular question (that means it’s the one in the title ^^). The answer was so thorough, and so thoroughly interesting, that I felt compelled to share it with the rest of the world. The following is not edited in any way except for correcting formatting errors due to transfer of media.

One quick note – the author of the comment is the first person mentioned with a link, Dr. Suzanne Sadedin (PhD Zoology). follow the link to see her other comments. Other names listed in the preamble are people of note who upvoted her comment on Quora.


Suzanne SadedinPhD in Zoology from Monash University.
Votes by Edgar A. Duenez-Guzman (3.5 years of Postdoc experience in Evolutionary…)Ray Duncan (MD, FAAP. Graduated from UCLA Medical School 19…)David Chan (MD from UCLA, Stanford Oncology Fellowship)Sandeep Venkataram (PhD Candidate in Evolutionary Biology at Stanford)Frank James Wilson (Retired Pulmonologist, Critical Care Physician,…), and 1970 more.
I’m so glad you asked. Seriously. The answer to this question is one of the most illuminating and disturbing stories in human evolutionary biology, and almost nobody knows about it. And so, O my friends, gather close, and hear the extraordinary tale of:
Contrary to popular belief, most mammals do not menstruate. In fact, it’s a feature exclusive to the higher primates, certain bats, and elephant shrews (dogs undergo vaginal bleeding, but do not menstruate). What’s more, modern women menstruate vastly more than any other animal. And it’s bloody stupid (sorry). A shameful waste of nutrients, disabling, and a dead giveaway to any nearby predators. To understand why we do it, you must first understand that you have been lied to, throughout your life, about the most intimate relationship you will ever experience: the mother-fetus bond.Isn’t pregnancy beautiful? Look at any book about it. There’s the future mother, one hand resting gently on her belly. Her eyes misty with love and wonder. You sense she will do anything to nurture and protect this baby. And when you flip open the book, you read about more about this glorious symbiosis, the absolute altruism of female physiology designing a perfect environment for the growth of her child.If you’ve actually been pregnant, you might know that the real story has some wrinkles. Those moments of sheer unadulterated altruism exist, but they’re interspersed with weeks or months of overwhelming nausea, exhaustion, crippling backache, incontinence, blood pressure issues and anxiety that you’ll be among the 15% of women who experience life-threatening complications.From the perspective of most mammals, this is just crazy. Most mammals sail through pregnancy quite cheerfully, dodging predators and catching prey, even if they’re delivering litters of 12. So what makes us so special? The answer lies in our bizarre placenta. In most mammals, the placenta, which is part of the fetus, just interfaces with the surface of the mother’s blood vessels, allowing nutrients to cross to the little darling. Marsupials don’t even let their fetuses get to the blood: they merely secrete a sort of milk through the uterine wall. Only a few mammalian groups, including primates and mice, have evolved what is known as a “hemochorial” placenta, and ours is possibly the nastiest of all.Inside the uterus we have a thick layer of endometrial tissue, which contains only tiny blood vessels. The endometrium seals off our main blood supply from the newly implanted embryo. The growing placenta literally burrows through this layer, rips into arterial walls and re-wires them to channel blood straight to the hungry embryo. It delves deep into the surrounding tissues, razes them and pumps the arteries full of hormones so they expand into the space created. It paralyzes these arteries so the mother cannot even constrict them.What this means is that the growing fetus now has direct, unrestricted access to its mother’s blood supply. It can manufacture hormones and use them to manipulate her. It can, for instance, increase her blood sugar, dilate her arteries, and inflate her blood pressure to provide itself with more nutrients. And it does. Some fetal cells find their way through the placenta and into the mother’s bloodstream. They will grow in her blood and organs, and even in her brain, for the rest of her life, making her a genetic chimera.

This might seem rather disrespectful. In fact, it’s sibling rivalry at its evolutionary best. You see, mother and fetus have quite distinct evolutionary interests. The mother ‘wants’ to dedicate approximately equal resources to all her surviving children, including possible future children, and none to those who will die. The fetus ‘wants’ to survive, and take as much as it can get. (The quotes are to indicate that this isn’t about what they consciously want, but about what evolution tends to optimize.)

There’s also a third player here – the father, whose interests align still less with the mother’s because her other offspring may not be his. Through a process called genomic imprinting, certain fetal genes inherited from the father can activate in the placenta. These genes ruthlessly promote the welfare of the offspring at the mother’s expense.

How did we come to acquire this ravenous hemochorial placenta which gives our fetuses and their fathers such unusual power? Whilst we can see some trend toward increasingly invasive placentae within primates, the full answer is lost in the mists of time. Uteri do not fossilize well.

The consequences, however, are clear. Normal mammalian pregnancy is a well-ordered affair because the mother is a despot. Her offspring live or die at her will; she controls their nutrient supply, and she can expel or reabsorb them any time. Human pregnancy, on the other hand, is run by committee – and not just any committee, but one whose members often have very different, competing interests and share only partial information. It’s a tug-of-war that not infrequently deteriorates to a tussle and, occasionally, to outright warfare. Many potentially lethal disorders, such as ectopic pregnancy, gestational diabetes, and pre-eclampsia can be traced to mis-steps in this intimate game.

What does all this have to do with menstruation? We’re getting there.

From a female perspective, pregnancy is always a huge investment. Even more so if her species has a hemochorial placenta. Once that placenta is in place, she not only loses full control of her own hormones, she also risks hemorrhage when it comes out. So it makes sense that females want to screen embryos very, very carefully. Going through pregnancy with a weak, inviable or even sub-par fetus isn’t worth it.

That’s where the endometrium comes in. You’ve probably read about how the endometrium is this snuggly, welcoming environment just waiting to enfold the delicate young embryo in its nurturing embrace. In fact, it’s quite the reverse. Researchers, bless their curious little hearts, have tried to implant embryos all over the bodies of mice. The single most difficult place for them to grow was – the endometrium.

Far from offering a nurturing embrace, the endometrium is a lethal testing-ground which only the toughest embryos survive. The longer the female can delay that placenta reaching her bloodstream, the longer she has to decide if she wants to dispose of this embryo without significant cost. The embryo, in contrast, wants to implant its placenta as quickly as possible, both to obtain access to its mother’s rich blood, and to increase her stake in its survival. For this reason, the endometrium got thicker and tougher – and the fetal placenta got correspondingly more aggressive.

But this development posed a further problem: what to do when the embryo died or was stuck half-alive in the uterus? The blood supply to the endometrial surface must be restricted, or the embryo would simply attach the placenta there. But restricting the blood supply makes the tissue weakly responsive to hormonal signals from the mother – and potentially more responsive to signals from nearby embryos, who naturally would like to persuade the endometrium to be more friendly. In addition, this makes it vulnerable to infection, especially when it already contains dead and dying tissues.

The solution, for higher primates, was to slough off the whole superficial endometrium – dying embryos and all – after every ovulation that didn’t result in a healthy pregnancy. It’s not exactly brilliant, but it works, and most importantly, it’s easily achieved by making some alterations to a chemical pathway normally used by the fetus during pregnancy. In other words, it’s just the kind of effect natural selection is renowned for: odd, hackish solutions that work to solve proximate problems. It’s not quite as bad as it seems, because in nature, women would experience periods quite rarely – perhaps as little as 7-10 times in their lives between lactational amenorrhea and pregnancies.

We don’t really know how our hyper-aggressive placenta is linked to the other traits that combine to make humanity unique. But these traits did emerge together somehow, and that means in some sense the ancients were perhaps right. When we metaphorically ‘ate the fruit of knowledge’ – when we began our journey toward science and technology that would separate us from innocent animals and also lead to our peculiar sense of sexual morality – perhaps that was the same time the unique suffering of menstruation, pregnancy and childbirth was inflicted on women. All thanks to the evolution of the hemochorial placenta.

The evolution of menstruation: A new model for genetic assimilation
Genetic conflicts in human pregnancy.
Menstruation: a nonadaptive consequence of uterin… [Q Rev Biol. 1998]
Natural Selection of Human Embryos: Decidualizing Endometrial Stromal Cells Serve as Sensors of Embryo Quality upon Implantation

Credits: During my pregnancy I was privileged to audit a class at Harvard University by the eminent Professor David Haig, whose insight underlies much of this research. Thanks also to Edgar A. Duenez-Guzman, who reminded me of crucial details. All errors are mine alone.”

I thought you might like that. As previously mentioned, this is ALL the work of an amazing doctor of Zoology and quora answerer, and she should get as many hits as all the humans can give for her amazing insights into the human reproductive process as it affects women.

A Belated Response to a Serious Reply

Hoo boy. So I’ve been avoiding answering this post for about three years now, for various reasons – including such hits as ‘I actually HAVE a life outside of blogging’, ‘I’m obviously not going to be able to have a constructive discussion with someone whose mind is already made up’, and of course ‘god, that’s a lot of text to go through’. But, hey, it’s the holiday season, I’m between quarters in college, and I was clearing out my spam when I remembered that I’d never replied to this post. And that’s just plain not fair. So, with fair play and hard work in mind, let’s roll up our sleeves and get to it. This is a reply to a response Deanna made to a post, so I suggest you refresh yourselves here.

My replies will be bolded.

I have been a pro-life activist for most of my adult life and know hundreds more.

So you know a bunch of people who share your opinions, and you’re loud and proud about advocating for those opinions to carry legal weight. Good for you, and I mean that sincerely – we all need to advocate for that which we believe.

However, that doesn’t establish any kind of medical credential that would put you on the same playing field with an expert in this medical procedure. I’ve been an advocate for abortion rights since I was very young, but that doesn’t make me an expert in the procedure – That’s why I let an expert speak, and didn’t really add anything to it.

I ran a crisis pregnancy center.

So – wait. As a credential, you’re presenting the fact that you ran a center that, and I quote wiki here, “is a non-profit organization established to counsel pregnant women against having an abortion.” This seems to be almost indistinguishable from your prior credential of political advocacy, although it seems -to be honest- a bit more predatory than just e-mailing your congressman.

I have counseled post abortive women. I have counseled pre-abortive women.

While I have no information one way or the other, I’m going to assume from the way this is written that you have no professional credentials that would qualify you as a counselor – outside of your religious and political beliefs, of course.

I have done massive amounts of research on abortion, the reasons for it, and it’s results.

Bully for you. I’m sure that just about anybody could make the same claim, but without an objective reference point such as professional certification, I have no real frame of reference for what you consider ‘massive’ – so I’m going to have to treat your claim skeptically.

I am a Christian.

Which has what exactly to do with this, outside of determining your opinion praejūdicium based on modern interpretations of some ancient tribal customs? I assume that you have followed these customs since birth or near as makes no difference, which sort of defines prejudice – A preconceived preference or idea; to judge prematurely and irrationally. Very good of you to recuse yourself for bias, though.

I am a mother. I have lost two children to miscarriage and I know fetal loss.

Which has what, exactly, to do with abortion? You’re a mother. Good for you, but I have a mother, and siblings with children, who feel as strongly about abortion, and in the opposite direction; so obviously parenthood (and fertility in general) does not confer some magical insight or authority with regard to abortion rights. The fact that you’ve miscarried, while perhaps regrettable, still does not make you an expert in getting an abortion.

I am an adoptive mother. I am a foster parent. I am the mother of a special needs child

See the above response.

and I am the survivor of a failed abortion attempt therefore I can honestly say that I know a little bit about this issue.

Oh? You have particularly vivid memories of the procedure? </snark>

The author of this article made some statements that are untrue. I would like to answer each one of these by stating the truth from the perspective of someone who actually lives it from the pro-life activist side.
1) “We all know that anti-abortionists aren’t really “pro-life,” they are “pro-forced birth.” This is a completely untrue statement. What we are is pro-human. We sincerely care about these women and their situations, we care about the baby and we care about the clinic workers. We know that these babies are human beings and because of that fact we believe that they should be protected.

I’m sorry, dear, but know isn’t a word to be taken lightly. You can’t know any such thing without some sort of divine power, which I certainly do not cede to you. In addition, the thing which will eventually become a human being is quite emphatically not a human being at the point at which abortion routinely is carried out. It’s a tiny collection of cells that has no more capacity for feeling or thought than your toenail clippings, and perhaps less. The reason I can say this authoritatively is because of a simple understanding of how the nervous system develops. Since that is a subject far too involved for the scope of our current discussion, I’ll let the curious do their own investigation.

We also know from our

Okay, I’m sorry, I noticed the change in tense – Is there a reason? Are you speaking in the royal ‘we’? To which group or organization are you referring to?

research and interviews with hundreds of post abortive women and 38 years of experience since Roe V Wade that abortion wounds women. It wounds them in their souls, in their bodies and in their spirits.

But hey, two out of three of those don’t exist in any measurable way, so that works. In all reality, I understand that what you’re talking about here is the very real religious/cultural psychosis that can overtake someone who engages in a religious or cultural taboo (based upon culture of birth/upbringing). It’s sad, however, that you have to inject mysticism and fuzzy logic words into your argument.

Instinctively women were made to protect and nurture the child that they carry. This is a scientific fact.

Unlike the rest of your arguments, this much is true – However, I should point out that there is also a biological drive for men to inseminate as many partners as possible. This doesn’t mean that every man has the desire to do so, nor does it follow that there is some sort of damage caused by not doing what your body is programmed to prefer.

When that process is cut short they suffer at some level emotionally.

This is most likely (according to current psychosocial, sociological, and biological research) more because of cultural bias and upbringing, than anything inherent to the act itself. In effect, ma’am, you’re arguing that people need to be MORE supportive of those who make the difficult decision to abort their unwanted pregnancy. Brava. *slow clap*

It is documented that 70 % of women who have abortions are at high risk for some sort of negative emotional fallout, some of it severe. (you can go to “after abortion dot org” for exact statistics and documentation.

Wey-hey, statistics and documentation (even if you’re leaving it to me to do the research!) I’m impre-oh, wait a minute. All you did was cite a website which is (very specifically) part of the anti-abortionist movement. Fine, I suppose, but not the place to look for unbiased research. Try instead to find independent, peer-reviewed research to support your claims (along with the journal and issue/date of publication). For instance, 

Fergusson, D. M. et al. (2006). Abortion in young women and subsequent mental health. Journal of Child Psychology and Psychiatry, 47, 16-24.

And if possible, summarize the protocols and results for those who can’t afford to purchase a subscription to the publication service. For instance, the results of the research paper I cited above are summarized thusly:


Pregnancy delivered and never pregnant used as comparison groups. Controlled for demographic, family of origin, history of abuse, partner, personality, and mental health history variables. National sample, high retention, low concealment, thorough assessments of outcomes.

Results of research: 

27% of women who aborted reported suicidal ideation. The risk of suicide was 4 times greater for women who aborted compared to women who had never been pregnant, and more than 3 times greater for women who delivered a child compared to women who had never been pregnant.

Huh. It looks like in that paper the damaging emotional fallout was pretty close to the same as post-partum after a normal birth. Who would have thought.

One more, just so you don’t accuse me of cherry-picking evidence that supports my argument:

Rue, V.M. et al.(2004). Induced abortion and traumatic stress: A preliminary comparison of American and Russian women. Medical Science Monitor 10, SR5-16.


Controlled for stressors pre-and post-abortion, demographic and psycho-social variables (including abuse and parental divorce, etc.). Women specifically asked if they believed the abortion was the cause.


36.4% of the American women and 2.8% of the Russian women respectively reported suicidal ideation.

Bonus, this one was a cross-cultural study, too! And look, it turns out that culture may have a huge impact on emotional fallout from an abortion!

We also know that since Roe v Wade there have been 300,000 cases of breast cancer directly connected to abortion. (You may contact me at **********************(e-mail removed so you don’t get a bunch of spam  – ed) for a link to this documentation. I cannot post it here because hyperlinks are not allowed and it is too long to reasonably type out.)

a) I don’t do other people’s research for them,

b) What, you think it’s easy for me to type out full summaries of research? Put in some effort, or don’t make the point.


c) Honestly I wouldn’t e-mail someone I don’t know personally (très collant), or trust any links an unknown person sent me to be virus-free. So I’ll pass, thanks, and consider the point above to be unproven, argumentative, and potentially a prima facie lie with malice aforethought.

We also know that there are over 300 documented cases of maternal death during abortion since Roe V Wade and many more that go unreported.

IF that’s true (there’s the royal ‘we’ again) then that’s 300 in almost forty years (37 at time of this article originally being written, 40 as of today). That means that an average of 7.8 women a year die from complications during an abortion procedure. By contrast, the death rate (during childbirth) in the US per hundred freaking thousand reached its lowest point in 1987 at 7.2(CDC). Total births in 1987: 3,829,000 (Associated Press, Aug. 10, 1988).

Total births divided by a hundred thousand births, times 7.2 women dying per hundred thousand, and the number we reach for 1987 alone (the LOWEST it’s been that we have records for) is 2,757. Just under three thousand women a year in the US died in childbirth in 1987. That is the lowest accurate maternal mortality figure on record. 

Phht. Your statistics may be accurate here, but you’re making a mountain out of a molehill so tiny the poor little guy has to sweep atoms off his front porch or they’ll block the entrance.

This is not to mention the bowel perforations, the hysterectomies, the bleed outs and a host of other medical issues.

Were you going to mention all the potential side effects and medical issues involved with carrying a child to term? No? Yeah, I thought not.

Again, I have documentation, contact me if interested.


The point that I am making is that abortion is not as safe as pro-abortionists would have you believe and we know that so our goal is to try and warn women of the dangers in all of these areas.

Oui, nous l’obtenons. Vous voulez dire aux gens quoi faire avec leurs aines. Rejoignez le parti ouvrier allemand national-socialiste, ne pliez pas à nos oreilles.

I’d be more sympathetic of your cause, or of you in particular, if your arguments were backed up by solid evidence. Instead, they’re emotional, and yet you dress them in science and couch them with vague danger words. I’m beginning to lose my patience with you.

Furthermore, a surprising number of women still believe the old form of pro-abortion propaganda that says that the fetus is “just tissue” or “products of conception” or a “blood clot” and when they find out that the baby looks like a tiny human at 8 weeks with a heartbeat by 18 days they are crushed, many turning to drugs or worse to ease their conscience.

I’ve seen sonograms of babies who were FAR further along, and even then they were like little aliens (when they were visible at all). At 8 weeks, aliens without a nervous system, so there’s that.

We want to give them the information ahead of time (thus the sonogram bills in legislature) to save them the emotional pain that they will likely endure post abortion. So, our motive is not that we don’t care or that we are women haters or that we want to control their wombs and be “forced birthers”, on the contrary, we care about women and don’t want them to go through these things.

You know what? Your motivations don’t really enter into this. I don’t honestly care whether your intentions are good, because you can still do amazing amounts of harm with only the best of intentions.

Furthermore, clinic worker after clinic worker and many abortion doctors who have left the business all testify that it was extremely hard on them emotionally and that “their families fell apart” etc., when they were doing abortions. We care about them also.

So much that fanatics you feed this stuff to bomb their places of business.

Most pro-lifers spend many hours in prayer for these people.

And you’re touting this on an atheist’s blog because…?

Some stand in the rain, the sun, storms and snow all while being belittled, criticized and mis-understood all because we care about humanity. We are not about forcing our beliefs on others and all the other junk that pro-abortion people say. It is about true compassion.

I cite my earlier comment on motivations and intentions.

2) The “pro-coerced birthers” think that these are immoral women who should be punished for their (sex) sins with an innocent child. Then they complain about “welfare mothers” who need money to support their children. Those “precious babies” become children who they don’t want to feed. Aren’t Christians supposed to provide charity for those who need it?

Most pro-life Christians go to churches that have programs,some of them massive para church organizations, that feed, clothe and house hungry children.

With a healthy dollop of (take your pick): Condescension, moral snobbery directed at the parents (and overheard by the kids), religious proselytizing, attempted forcible conversion, and of course sexual abuse (Catholics). Fun times. (Before you ask, yes, I’ve seen these first hand – with the exception of the whole catholic thing, but that’s what the news is for.)

These pro-lifers financially support these programs through their churches.So, they do take care of the children.

Bully. Any of them pay for the full ride 0-18? No? Didn’t think so. And when you say ‘take care of’, I don’t think you’re including the cost of psychological counseling (from being raised in an unloving household), college tuition (if they’re lucky enough to get good grades), or any of the other ancillary costs involved in bringing a healthy, socially well-adjusted child into the world. No, you’re talking cast-offs and soup-kitchens. I’m sure it salves your conscience, but it doesn’t do much more than ensure a living nightmare for the kids.

Programs such as Feed the Children, The 700 club, James Robinson, Warm Blankets International, Rainbow Kids, etc. (I could go on and on for pages listing them) are all Christian based and they are doing EXACTLY what the author said that we do not do.

See my point above.

Furthermore, many if not most adoption agencies are christian based and they are placing children from all over the world in loving adoptive homes. I have personally adopted 4 of them, one special needs with Fetal Alcohol Syndrome, another special needs with parental mental health issues, and one teen. I have supported Orphan relief efforts as well as inner city efforts. I am a certified foster parent. There are many many more who do much more than I do, some giving up lucrative careers to help these children. Furthermore, we start unwed mothers homes and crisis pregnancy centers that furnish baby furniture,car seats, maternity clothes, infant clothes and any other supplies needed in order to help with practical needs. We have food programs, housing programs and medical programs. I would like to ask the author where she gets her information that we do not try to take care of these children. Also, we do not see children as a punishment, but rather a gift and a miracle, therefore our intention could not possibly be to “punish” the women.

Okeydokey, so see my points above re: care, ‘Intentions’, anecdotal experience not qualifying as a professional opinion, annnnd… yep, that’s about it.

3) They just want to keep punishing women. In light of what I just said, I think this point has been refuted.

See the above re: Intentions.
4) But I can tell you that the people who oppose abortion have no feelings of any kind for the poor women who have to make the terrible decision to end a pregnancy for whatever reason.. Again, point refuted.

Again, See Intentions v. actions. If your intentions are good, and your actions are causing harm, and you refuse to cease when informed of the harm, then it is reasonable and ethical for a person to assume that you are intentionally causing harm, whatever your stated intentions.

5) Last time I checked, abortion was legal in this country . Legality does not dictate morality. Slavery, human trafficking and prostitution have all been legal in this country but none have been moral. Morality should dictate legality.

You know what? I’m almost inclined to give you this one. However, since morality is cultural and changes based on the whim of the community at large, I’d suggest replacing that with ethics – a branch of philosophy that involves systematizing, defending and recommending concepts of right and wrong conduct.
6) They want to end abortion because they love those theoretical innocent children. No statement has ever been truer with the exception of the “theoretical part”. There is nothing more innocent than a baby growing inside its mothers womb. This is not a theory.

Yes, and? It ain’t a baby until it has a nervous system, a brain stem, a place where cognition can happen, thoughts and emotions and memories. Seven months in, you’ve got me hooked. Right now? All you’re doing is spouting a slogan. Your ‘intentions’ are showing, dear.

In summary I would just like to add this. As I said, I am an abortion survivor. I have lived a full life. It has been far from perfect and would probably surprise most. I have lived through pain and death and sorrow and I have known loss but I have also known peace and joy and love. But regardless, it has been MY life, not my mother’s or not the pro-abortionists life, no it has been MINE and NO ONE had the right for ANY reason to take that from me. I am that fetus, here from the womb, that one who you say has no worth, that one that all of your pro-choice arguments have decided doesn’t deserve to be given a chance to live. I am that one that trumps my mothers reproductive rights and her wombs sovereignty. It is my life. It is not yours to take. There have been over 53 million abortions since Roe V Wade with over 100,000 of those each year being late term. Those lives are no different than mine. Every single one of those deserved the right to live THEIR lives. Abortion is horrendous for both the mother and the baby and we have been brainwashed to think it is acceptable. I am living proof that it is not.

*hums* ‘I am strong, I am invincible, I am WOMAAAAAAN’ …. 

I don’t honestly care. Your personal, anecdotal story of … whatever the bleep that was, does not touch me in the slightest – because you’re using it as a cynical, manipulative ploy to engage my empathy and win an argument… on the internet (Good luck with that, by the way). It doesn’t add anything at all to your arguments. All it does is make me think less of you as a person.

Any idea what this is? Sherlock Holmes needs your help, O-chem students!

Look, I’m in O-chem, and I recently watched an episode of the show ‘Elementary’ in which Sherlock(!) Holmes(!) gets stumped on a chemical structure which may have implications in a case. Thing is, I’m a second-year chem student, and I recognize most of the structures involved. photo after bump. Continue reading “Any idea what this is? Sherlock Holmes needs your help, O-chem students!”

What I’m doing.

This is why I can’t blog and update a lot… I’m busy doing things like this… Gah.

Dicamptodon tenebrosus

Human Interactions

Bio 212, Winter Quarter


Figure 1:  Coastal Giant Salamander (Dicamptodon tenebrosus) (Nafis)

Dicamptodon tenebrosus, the Coastal Giant Salamander, has its habitat in fast-flowing clear streams and forest floors (within ~50 meters of those streams), and rarely comes in contact with human beings, avoiding heavily populated settlements (California). Given that information, one might assume that they would be subject to heavy habitat loss through logging, siltation of their steams, and other human activities. The reality is a bit murkier.

The Canadian government, through its environmental arm, the Ministry of Environment, Lands, and Parks, has placed tenebrosus on its provincial red list (candidates for threatened or endangered status), because inside of the borders of Canada, the area in which tenebrosus is found is quite small, and may be threatened by just such behavior as was discussed before – logging and siltation of streams reducing the available habitat (Blood).

However, the IUCN red list has them listed as ‘Least Concern’, citing ” wide distribution, presumed large population,” and that “it [tenebrosus] is unlikely to be declining fast enough to qualify for listing in a more threatened category.” (Hammerson). The wide distribution the IUCN cites stretches over 700 miles linear, from northwestern California to the Chilliwack drainage in B.C., Canada. This does not include breadth of distribution, which may be wide or narrow, depending on local area conditions.

The IUCN is not alone in their designation. The Washington Herp Atlas cites state and Global (US) conservation statuses of S5 (“Demonstrably widespread, abundant, and secure in the state; believed to be ineradicable under present conditions”) and G5 (“Demonstrably widespread, abundant, and secure globally, though it may be quite rare in parts of its range, especially at the periphery”), respectively (Hallock).

Does this mean there is no cause for concern? The answer seems to be both yes and no. While tenebrosus is in no immediate danger, future habitat losses due to unsafe logging practices, coupled with predation and the difficulty in doing species-count studies with a species so adept at hiding from exposure, raises the possibility of not knowing enough about population losses until they reach a critical mass.

In closing, while they only seem to be rare at the periphery of/outside of their natural habitat, these animals live in a habitat directly impacted by logging and other human industry. Safe logging and forest habitat preservation practices will go a long way toward making sure tenebrosus never gets endangered, keeping these wonderful animals around for future generations.



Paul Zak on the Trust Molecule

An amazing talk hosted on TED (of course) – This video has (if only figuratively) blown my mind. I wish I could get my hands on some pharmaceutical-grade oxytocin and dose the world (Or at least the GOP – they seem to need it more than most). ^^

For those who can’t see the video above, here’s the link:

The Flower: An Animated Allegory

I think pretty much everyone needs to see this video, as it sums up the truth of the situation pretty well. We may not all agree, and this video comes off a little biased, I will admit, but the objective truth agrees with the majority of the (allegorical) statements made in this cartoon.

TL: DR – Watch this. It’s Fawkin’ true, mate.