Biology of a fragile pain intolerant alien race?

Question

So I'm working on this alien race that is very similar to humans with some minor changes and one major change.

The biggest change is that they are very pain intolerant. This pain intolerance is apparent to them and when they started dealing with us it became more so. And with this particular aspect they actually started developing a lot of their cultural around it.

This is so that instead of a feature in them that got removed with time or they started actively working to raise their pain tolerance, they accepted it and started working around that. Because I know it might seem reasonable that they would just try to be more pain tolerant, but that is a part of the premise and I don't feel the need to change it.

Now the level depends on the person a bit but generally they are something close to 20%-30% of a pain tolerance of a human being.

And over the course of their history they started developing martial arts and fighting that is based on the concept of first strike and speed. That is if you are facing another of your own kind it all revolves around delivering a first strike, or in the rarest cases, a second strike and that's it.

Of course now they are space traveling people, and so they developed a complex and advanced means of fighting. And they mostly use armors to protect them. But so far they can't biologically engineer themselves to be more pain intolerant. And the rest I think is irrelevant.

Now my question is: Starting from what I said what is their biology going to be like, especially as opposed to us?

I don't know much about biology and so if it needs to be broken down to particular points I would do so, but it would be helpful to understand what those point are in the first place. And to make it clear I'm not looking for a detailed, hypothetical one I know, breakdown of their genes or nervous system. Just the basic stuff.

Example: How the Turians, Mass Effect, have this metallic carapace around their bodies because they originated on a planet that is exposed to a lot more radiation that others.

This helps in starting with the one problem I'm trying to solve: what is their biology going to be.

Answer 1

Hyperalgesia and other conditions.

So apparently you want them to be very similar to humans, but with very little changes other than extreme intolerance towards pain? Well lucky for you and unlucky for us, there are various conditions the human body can undergo that directly regard pain,among them, the one that seems to best suit your aliens is a variation of hyperalgesia. Let's take a look at the Definition of hyperalgesia by the NCI dictionary of cancer terms:

An increased sensitivity to feeling pain and an extreme response to pain. Hyperalgesia may occur when there is damage to the nerves or chemical changes to the nerve pathways involved in sensing pain. This may be caused by tissue injury or inflammation or by taking certain drugs, such as opioids, for chronic pain. People with hyperalgesia tend to feel extreme pain even though an injury or medical condition has not gotten worse. This pain may get worse over time, and it may extend to other areas of the body. It may also become a new or different type of pain than the original pain.

Sounds much like what you apparently wish for,although not quite. Rather than not being capable of dealing with pain, these people have an overreaction to it and to certain stimuli that usually wouldn't hurt.

So approaching how it worked and how it increased after contact with us: perhaps your aliens could've already possess their own variation of this condition, although in their case this increased sensitivity to stimuli could be genetic and would've been useful for their survival (maybe a plague spreaded by a certain bug-like alien devastated their planet's population and only those who had increased sensitivity could detect the bugs landing on them when most wouldn't, perhaps other event. Point is having increased pain would've somehow helped them survive, being passed on; at least from a natural selection point of view).

Perhaps over contacting us, they could've somehow developed a variation of hyperesthesia, which in turn further increased their sensitivity (please understand that I'm not a doctor or someone experienced in the area, so I cannot affirm that this would be an easy or normal thing to happen, even to humans, as it seems more related, according to Jeanne Siaud-Facchin, to gifted people who would process more information in a shorter period of time).

Now their martial arts: you said that it is focused on the first and second strike in a worst case scenario. With them feeling increased pain from basically everything and their anatomy being seemingly similar to ours, that sounds very reasonable, as they're exploiting the increased pain to cause the opponent to faint, more specifically suffer vasovagal syncope.

Vasovagal syncope is one of the most common causes of fainting. In this situation, the balance between the chemicals adrenaline and acetylcholine is disrupted. Adrenaline stimulates the body, including making the heart beat faster and blood vessels narrower, thereby increasing blood pressure. Acetylcholine does the opposite. When the vagus nerve is stimulated, excess acetylcholine is released, the heart rate slows and the blood vessels dilate, making it harder for blood to defeat gravity and be pumped to the brain. This temporary decrease in blood flow to the brain causes the fainting episode.

The key point here is that the vagus nerve can be stimulated by pain, as well as other noxious stimuli. Your aliens, assuming A very similar anatomy of their nervous system, exploit this to focus on fast strikes at specific regions, likely trying to apply as much pressure as possible, thus resulting in blows that, to humans, would already hurt quite bit, and to their own race, incredible pain that results in fainting. Oh, they're somehow still awake? Hit them again.

Answer 2

Vestigial Exoskeletons

Pain has a lot of potential underlying sources - muscle, tendon, nerve, bone, etc - but evolutionarily it stems from "your body telling you something is wrong". In humans, one of the most straightforward, painful occurrences is a compound fracture, which makes sense because you've suddenly got a lot of sharp bone bits moving through important tissues:

• Compound fractures in a limb may hit the femoral/brachial artery, but at the very least it mucks up muscle movements in that region.
• We don't have many large bones in our torsos, but when ribs take too much impact they can easily puncture a lung, which is apparently incredibly painful

In human martial arts, striking first isn't as imperative because most of our body can take a hit or two. Conversely, if your body can't take any hits anywhere, striking first becomes very important.

How did this evolve?

They come from a planet with high winds and lots of dust, so their exoskeletons require constant repair against this ablation. The outer layers renew fairly quickly with minor abrasions, but inner layers don't need to because they're rarely exposed. The latter is something that hasn't been selected against because like Earth insects, they molt, and therefore the inner layers need to be more durable than flexible.

The vestigial bit is pretty easy. They're a spacefaring race, so like humans, they've probably been breeding for intelligence (rather than physique) for quite some time. Over the long term, factors like exoskeletal fragility won't be selected against as heavily in a sentient race as they would in a non-sentient one.

Unfortunately, things start to go poorly if they do get seriously injured. With a fast-growing exoskeleton that's suddenly partly internal, the consequences end up a lot like my favorite cringe-worthy disease, Fibrodysplasia Ossificans Progressiva. Unless they get to a hospital very quickly and undergo major surgery immediately, these exoskeleton fragments continue to grow internally, eventually killing them

Answer 3

They used to have shells.

Approproate pain thresholds are set by environmental pressure. Too low your animal is too reckless and gets eaten. Too high your animal is too cautious and doesn't breed. Both stops the wrong threshold being passed on.

So your sudden pain intolerence must be a recent or artificial occurence. I suggest your creatures have a hard exoskeleton with sensitive nerve endings underneath the skeleton. This gave an appropriate pain threshold.

But somewhere along the road to civilisation, they realised these big clunky exoskeletons are great for protection but not much use for fine-control, such as texting on a mobile phone, or even sitting in a room looking back and forth between a group of people.

Since the protection is not needed anymore, many members of the special purposefully starve themselves of the mineral needed to grow the exoskeleton. So they remain in a permanently pre-moulted and sensitive state, but with very dexterous fingers.

Most of the people humans will ever encounter fall into this category.

On the home planet having much of a shell (you can regulate shell thickness/weight by rationing mineral intake) is now looked down upon in high society. This originally comes from how people with menial jobs might keep some shell for the physical protection rather than wearing safety gear.

Two parallels in our world:

1. In some areas very short haircuts are considered "working class". Historically this is because people who worked in a factory keep their hair short to prevent it getting caught in a machine.

2. A rebellious teenager might announce to their parents "I am getting a piercing and/or tattoo and you can't stop me!". In this world they instead announce they're growing out their shell and you can't stop me.