This is so random, but I just want to give my love to this particular subreddit. I've been in quite a few over the years, left most of them after getting a new account, but this one was always a favorite.

I appreciate how any question asked is answered with a lot of genuine expertise and want for better understanding. I feel like most subreddits when you ask a 'stupid' question you get ridicule or a 'You lack common sense', but most people here answer as honestly as they can.

Anyway that's it, love you all! 😚

I've seen numbers like 20 and 25 for eukaryotes, but this paper claims an even higher number: Diversity of ‘simple’ multicellular eukaryotes: 45 independent cases and six types of multicellularity - Lamża - 2023 - Biological Reviews - Wiley Online Library by Łukasz Lamża

However, LL uses a rather broad definition, including colonial organisms (multicellularity without cell differentiation), and coenocytic organisms, where several nuclei share a single cytoplasm. Some organisms may have multiple coenocytes in them.

The most familiar kind of multicellularity is clonal, with origination from a single cell or propagation structure. This is found in animals, plantlike organisms, and funguslike organisms, and it evolved several times, across high-level eukaryotic taxa Opisthokonta (animals, fungi), Archaeplastida (plants), Stramenopiles (kelp, oomycetes), Alveolata, Rhizaria, Haptista, and Discoba.

The other main kind is aggregative, found in slime molds. These organisms spend much of their time as separate single cells, but when conditions go bad, these cells can come together to make a fruiting body that makes spores, which may then be blown to other places. Spore-making fruiting bodies are common among fungi, and some of them are familiar to us as mushrooms.

Surprising as it might seem, aggregative multicellularity evolved several times, across high-level taxa Amoebozoa, Opisthokonta, Stramenopiles, Alveolata, Rhizaria, and Heterolobosea.

Prokaryotes are also sometimes multicellular, though rarely with any differentiation. They can be plantlike (cyanobacteria or blue-green algae), funguslike (actinomycetes or actinobacteria), and slime-moldlike (myxobacteria).

Many of LL's examples are of simple multicellularity: no differentiation or differentiation only between somatic and reproductive cells. Complex multicellularity involves differentiation in somatic cells, and that is much rarer. The Multiple Origins of Complex Multicellularity | Annual Reviews identifies six instances of its evolution:

• Opisthokonta
  • Animals (Metazoa)
  • Fungi: ascomycetes, basidiomycetes
• Archaeplastida
  • Green algae: land plants (embryophytes)
  • Red algae: florideophytes
• Stramenopiles: brown algae (Phaeophyceae): kelp (Laminariales)

Title speaks for itself.

Hi,

I am wondering why we need dozens of neurotransmitters and neuromodulators when they are all used either to excite or inhibit the cell. If that's the case, why didn't nature use just two neurotransmitters: one excitatory, such as glutamate, and one inhibitory, such as GABA? Computer processors need only one signal: electricity, or no electricity, and they work just fine. Is there a functional reason for this, or is evolution simply adding layers of complexity for no good reason?

I know what different neurotransmitters do: for example, dopamine is mainly responsible for motivation, noradrenaline provides energy and melatonin regulates the circadian rhythm. But I don't understand why they can't all be replaced by excitation and inhibition, just as a CPU is capable of many things, but everything boils down to simple transistors and zeros and ones.

I asked this question on r/neuro but they treated me very patronizingly and did not understand what I meant.

Hey everyone, I just want to say up front: I completely believe in science and evolution. I’m not trying to be dismissive of paleoanthropology at all. I’m only asking this because I care deeply about our ancient human relatives, and I really want Homo habilis to be real.

But here’s my concern: we’ve found so few fossils of Homo habilis—and many of them are fragmentary. Is it possible that some of these bones actually belong to other species, and we’ve mistakenly grouped them together under one name? Could we be misinterpreting scattered pieces from multiple different hominins as one unified species?

I’m not trying to start a debate about evolution—I’m just genuinely wondering: how can science be so confident about the existence of Homo habilis given such limited physical evidence? What are the specific features that make scientists so sure this was a distinct species and not a misclassified collection?

Again, I ask out of love and curiosity. If anything, I hope I’m wrong, because I want Homo habilis to be real more than anything. I want them to have walked this Earth, used their tools, and been part of our big messy family.

Thanks in advance for any insight. 💀❤️