[benlivengood]

There are still some cool edge-cases. Is a sperm cell alive? An X-chromosome sperm (do X-chromosome sperm have a (probabilistic N)-stage lifecycle?) Are red blood cells alive? Is every molecule of an organism that's alive also considered alive, or just the ensemble? If only the ensemble, are mitochondria alive?

[dandanua]

Also, why we consider a single human as living organism, but not a society? Single human without society is a pitiful and helpless chunk of meat, who unable to replicate btw.

[ealloc]

Sperm cells can be seen as a haploid phase of many organisms' lifecycle, so are alive by pretty much any definition.

In humans, the haploid phase of the lifecycle is single-celled, while the diploid phase is multicellular. In contrast, in mosses and fungi the haploid phase is multicellular while the diploid phase (sporophytes/zygote) is single-celled.

Red blood cells are discussed in the article.

[gus_massa]

> Is a sperm cell alive?

The unfertilized eggs of bees become drones, so they must be alive. As a side effect, this indirectly make bee-like insects evolve a lifestyle with a big colony with a queen.

In fungus, most of the life is as haploid (i.e. a single copy of the chromosomes, like sperm and eggs) instead of diploids (i.e. two copies of each chromosomes, like most of our cells.)

In some ¿unicellular organism? [I can't find a good link now] the haploid and diploid versions are almost equal.

[And plants are also weird, some have 4 or 6 copies of the chromosomes instead of 2.]