Here's the biological expedition team, in their turn of the last century fashion. When drawing and coloring these characters, I started attributing personalities to them based on, well, nothing but my own whims.
I figured the man to the left, apart from the group at the front of the mule line carrying a rifle in a laid back stance, was leader of the lot. He gets to carry the gun after all. What did biologists need firearms for? Specimen collection? Food collection? Anyways, he's wearing green, should he need to camouflage himself in the bushes.
Gentleman in the middle - he's mostly hidden behind mules, yet he's wearing the nicest outfit. Maybe he was excited about the photo op, and consulted his wife beforehand about which tie would best complement his jacket and hat. But then upon arrival at the shoot and seeing the casual attire of his fellow scientists, felt self-conscious and hid behind the mules. I've had those days where I suddenly realize that I hate my outfit, and can't do anything about it until I get home. I understand.
To the far right - he has no need for hats, like the sun shunning others. And thus he is the most tan. He's giving us a sideways look and is awkwardly holding rope attached to nothing, but he didn't know what else to do with his hands. He Obviously didn't really want his picture taken, but the guy in the green made him. He would much prefer to be following small mammal tracks at this very moment.
The Left Mule is pleased to have more contrasting coloring than her companion. She is particularly proud of her charcoal socks, and is happy to be carrying the canvas tent. The Right Mule likes his washed out colors just fine, thank you very much, but can't wait until the week is over and he trades packs with Other Mule, so he doesn't have to carry the wood box of microscopes, the corners of which keep poking into his haunches.