Most afterlife beliefs exclude life forms that are not Homo sapiens from passing onto the afterlife. I contend that these particular beliefs employ double standards and intellectual dishonesty by way of emotional exclusivity for humans. But to properly discuss and analyze the afterlife, one must know what comprises a living entity. Wikipedia has a great entry about the meaning of biological life.
Lets look at a few points in this Wikipedia article to get an idea of what biological life is:
In biology, an entity has traditionally been considered to be alive if it exhibits all the following phenomena at least once during its existence:
2. Metabolism, consuming, transforming and storing energy/mass; growing by absorbing and reorganizing mass; excreting waste
3. Motion, either moving itself, or having internal motion
4. Reproduction, the ability to create entities that are similar to itself
5. Response to stimuli - the ability to measure properties of its surrounding environment, and act upon certain conditions.
This is a good starting point for biological life, but Wikipedia also notes that this list is somewhat lacking:
These criteria are not without their uses, but their disparate nature makes them unsatisfactory from a number of perspectives; in fact, it is not difficult to find counterexamples and examples that require further elaboration. For example, according to the above definition, one could say:
-Fire is alive (this could be remedied by adding the requirement of locality, where there is an obvious feature that delineates the spatial extension of the living being, such as a cell membrane, although this would then discount fungi, and grasses from being alive).
-Stars could be considered living beings (for the same reasons as fire).
-Male mules are not alive as they are sterile and cannot reproduce.
-Viruses are not alive as they do not grow and cannot reproduce outside of a host cell.
-People who are impotent are not alive
Wikipedia then gets more specific regarding the definition of life by referring to biologists and terrestrial (Earth) life:
Biologists who are content to focus on terrestrial organisms often note some additional signs of a "living organism", including these:
1. Living organisms contain molecular components such as: carbohydrates, lipids, nucleic acids, and proteins.
2. Living organisms require both energy and matter in order to continue living.
3. Living organisms are composed of at least one cell.
4. Living organisms maintain homeostasis.
5. Species of living organisms will evolve.
All life on Earth is based on the chemistry of carbon compounds. Some assert that this must be the case for all possible forms of life throughout the universe; others describe this position as 'carbon chauvinism'.
For simplicity’s sake, lets confine our discussion of life to Earth-based, carbon life (all Earth life is carbon-based). Now that we have a good idea of what life is, lets compare specific examples. In case you don’t know, all organisms on Earth are divided into 5 "kingdoms": Bacteria, Protozoa, Fungus, Plants, and Animals. Despite the cries of many religious people, human beings (Homo sapiens) belong in the "animal" kingdom.
Let's compare humans to the Wikipedia criteria for being alive. It is pretty obvious that humans meet each requirement. What about jellyfish? Well, they meet all these requirements as well. Lets get a bit more basic. What about a tree? A tree meets these requirements just as well as a human does. What about mushrooms? So do they. What about bacteria, say, of the flesh-eating variety? Well, flesh-eating bacteria meet the "life" requirements just as well as humans do. All of these entities I mentioned share many of the same things: They all have DNA, they all reproduce, they all consume food and produce waste, they all meet the requirements for life equally.
Now that I've pounded that point home, I can make the connection to the afterlife. Why am I so concerned with what is and is not alive? Simple! To support a statement about the afterlife, which is:
To honestly support an afterlife-belief, one must do so for all entities that meet the "life" requirements. If an afterlife exists for humans, it must also exist for all bacteria, protozoa, fungus, plants, and animals.
The phrase "afterlife" means that a consciousness or soul will continue to exist after the physical death of a body. Life is defined as above thanks to a wonderful Wikipedia article. Therefore, there is no reason to think that Homo sapiens exclusively pass on to the afterlife. Indeed, there is no reason to think that any life form would not pass onto the afterlife.
From the animals and plants we eat, to the fungus we top our pizzas with, to the bacteria we massacre with every breath we take, to the dust mites that live and die on our skin, to the yeast we cook with and consume, all of these entities are equally qualified for afterlife membership if we are to think that humans are destined for an afterlife.
And here is the reductionist portion: All life forms are either single-celled or multi-celled. A single blood cell from a human is alive in that it, along with its counterparts (other human cells), works cooperatively to form a complete life form.
If a skin cell on a human dies, wouldn't it also qualify for afterlife-passage all by itself? If not, then what about an independent single bacteria cell? What about a single human embryo cell (before the cell division begins)?
I have heard of religious arguments (especially Christian arguments) that state that only humans go into the afterlife because only humans have sentience or a consciousness or soul. These arguments are not only unevidenced, but when the religious person submits criteria for the qualification of such a "soul" or "sentience," their assertion of human exclusivity can be proved demonstrably false. What I mean is, the criteria that a religious person can submit for the existence of a human "soul" or "sentience" can also be met by most, if not all, living species. And if any non-sapien members of the homo genus still existed, they would likely meet the criteria as well.
In addition, the "humans-only" afterlife argument looses strength when one looks at the pro-afterlifer's views on stem cell research or single-cell human embryo research. To destroy a stem cell or another form of single (not yet divided) human embryo cell is, according to pro-afterlifers, the murder of a human being, and that human (single cell) is imagined to pass on to the afterlife. This is a blatant double-standard and a complete violation of the religious person's previous criteria for having a soul or sentience, because these "human" cells are no more complex than the single celled bacteria found in everything from food, to snot, to breath. In addition, I contend that a dolphin (which would not qualify for afterlife existence according to most religions), meets the "soul" and "sentience" criteria much better than a human stem cell or embryo.
Multi-celled life is reducible to single cells, and therefore, the afterlife belief cannot be restricted to a given species of life form without the use of intellectual dishonesty and/or a double standard. Religious pro-afterlifers concede this point when they fight for the rights of human stem cells and embryos, but they turn around and deny this point when you ask them which life forms qualify for passage into the afterlife.