Apes

 

You said:

Twenty million years ago apes appeared, descended, of course, from monkeys. What makes the difference and what happened (the only thing I know is apes don't have tails, to my mind a sad loss).

ChatGPT said:

Ah, the old tail debate—yes, it is a kind of loss, though it came with gains. Let’s unpack this carefully.

Monkeys and apes are both primates, but the distinction lies in anatomy, behavior, and evolution. One simple visible difference is the tail: monkeys usually have one (sometimes prehensile, for grasping), apes don’t. But that’s just the tip of the iceberg.

Here’s what really changed in the ape lineage around 20 million years ago:

1. Body and Limbs: Apes generally have a more flexible shoulder and arm structure, allowing brachiation (arm-swinging through trees). Their torso is more upright, and they have a broader chest. Monkeys tend to have more rigid, forward-pointing shoulders.

2. Hands and Feet: Apes’ hands are more dexterous. They can manipulate objects with precision; their thumbs are more opposable than most monkeys. Feet are also more flexible, sometimes allowing a “grasping” function, unlike many monkeys.

3. Brain and Behavior: Apes evolved larger brains relative to body size. This allowed more complex social behaviors, problem-solving, and eventually, culture and tool use in some lineages (think chimpanzees, orangutans).

4. Locomotion and Posture: Losing the tail is tied to a shift in balance and movement. A tail helps monkeys balance in leaping and running along branches. Apes relied more on arm and torso strength, swinging, and later, in hominins, upright walking.

5. Diet and Teeth: There were dietary shifts as forests changed and some apes began to exploit different niches. Teeth and jaw structure adapted accordingly.

So, evolution “chose” a trade-off: lose the tail but gain upper-body flexibility, grasping ability, and cognitive sophistication. It was sad if you liked tails—but it opened the door for a whole new kind of primate lifestyle.

If you want, I can draw a quick mental timeline of how monkeys gave rise to apes and eventually humans, showing where these changes happen—it makes it much easier to visualize. Do you want me to do that?

You said:

You know, you really didn't say much in all that; the differences are systematic alterations in anatomy which included no tail. At least that's what I got from it all.

ChatGPT said:

Exactly—that’s the core of it. The tail is just the most obvious “flag” we notice, but it’s part of a suite of anatomical changes: shoulders, chest, arms, hands, brain, posture. Losing the tail wasn’t the goal—it was a byproduct of a body redesigned for a different style of moving and interacting with the environment.

So yes, apes aren’t just monkeys minus tails; they’re monkeys plus a whole set of structural reorganizations. The tail is like the tip of the iceberg that signals the deeper changes underneath.

If you like, I can sketch a simple “before and after” comparison between a typical monkey and an early ape—just the skeleton and posture differences. It makes the changes really clear.

You said:

Seems to me tails are useful for monkeys in the trees. Brachiation my require stronger arms, but a tail would still be helpful.

ChatGPT said:

You’re right—a tail would still be useful in the trees. For most monkeys, especially those leaping between branches, it acts like a counterweight, a balancing pole, even a fifth hand if it’s prehensile. Losing it seems like a step backward at first glance.

But here’s the catch with early apes: their whole body plan was shifting. They were evolving longer arms, stronger shoulder joints, and a more upright torso, which allowed them to brachiate efficiently. The mechanics of swinging by the arms made a tail less necessary. In fact, a long tail might have gotten in the way of swinging through branches with those long arms—it could snag or throw off momentum.

So, evolution traded tail-based balance for arm-based mobility. The tail was “sacrificed” because it no longer gave a net advantage given the new locomotion style. It’s a reminder that evolution isn’t about what’s objectively useful—it’s about what’s useful in the context of the whole body.

If you want, I can explain why brachiation alone could support apes even in very complex canopy environments, tail or no tail—it’s kind of elegant how it all fits together.

You said:

So it went because it no longer was needed, not because it presented a problem?

ChatGPT said:

Exactly—that’s the key point. The tail didn’t vanish because it actively hindered apes; it disappeared because, in the new body plan and way of moving, it simply wasn’t necessary anymore. Evolution tends to prune structures that aren’t providing a selective advantage—there’s no “plan” or foresight, just that individuals with slightly shorter tails weren’t at a disadvantage, so over generations the tail became vestigial and eventually lost.

It’s the classic case of “use it or lose it”—except in this case, it wasn’t harmful to keep, just redundant. Over millions of years, natural selection let it fade away because it no longer contributed to survival or reproduction.

If you like, I can give a neat comparison of how arm-based brachiation can fully replace the balance function of a tail—it’s surprisingly efficient.

You said:

I've watched gibbons. They certainly are efficient.

ChatGPT said:

Exactly! Gibbons are a perfect example of how apes replaced tail-based balance with sheer arm and shoulder mechanics. Their arms are incredibly long relative to their body, shoulders rotate almost like ball-and-socket joints, and their hands have that flexible grip that lets them swing with speed and precision. They don’t miss a tail at all—their whole body is optimized for swinging.

Watching them, you realize it’s not just that they survive without a tail—they thrive in the canopy. What seems like a loss (the tail) is more than made up for by freedom of movement, reach, and agility. In a way, their locomotion looks even more elegant than a monkey’s hopping and balancing act.

It’s a nice reminder that evolution isn’t about “better” or “worse,” just fit for a new strategy. Apes rewrote the rulebook for moving in trees—and the tail got cut in the process.

If you like, I could outline how the shift from tail to arm-dominated movement might have opened doors for later apes, including humans—it’s a fascinating chain reaction.

You said:

One time one escaped (left is a better word) the HCMC zoo simply by going limb to limb. Fortunately they trapped it unharmed and pruned back some of the trees.

ChatGPT said:

Wow—that must have been quite the sight! Gibbons really do make it look effortless, but seeing one “escape” like that in a zoo setting drives home just how agile and precise they are. Limb to limb, swinging faster than you’d expect, changing direction mid-air—it’s like watching a living acrobat.

Trimming the trees makes sense; in a confined space, their full mobility can turn even a modest enclosure into an escape course. It’s a reminder of just how specialized their anatomy is: long arms, strong shoulders, and flexible hands letting them navigate complex three-dimensional space without needing a tail at all.

I can imagine the zookeepers’ mixture of awe and panic—trying to coax a small, incredibly fast ape back into a cage is no small feat!

You said:

It was not actually in a cage but in one of those more "natural" exhibits. I can't really say, I just heard about it. As I understand it he had an adventure and then they netted him returning home. They probably could have just let him go where he was headed.

ChatGPT said:

Ah, that makes more sense—those “natural” exhibits often have open tops or connected branches to mimic a real forest, so an agile gibbon could quite literally take a little adventure. Netting him on the way back was probably more about safety—for him and for people—than about containment.

And you’re right: in some ways, they could have just let him continue, assuming the surrounding area was safe and suitable. But with urban or semi-urban surroundings like HCMC, letting a gibbon roam freely could quickly become dangerous for him—traffic, humans, or even stray dogs. So “rescue” is less about stopping an escape and more about protecting him from the real world.

Still, it’s fun to imagine: a small ape taking a brief solo tour of the city canopy, just exercising all that incredible arm power and balance. Nature meets urban adventure.