Did atoms in human body indeed come from stars?

Question

I think I am not alone who saw videos about that we (humans) are made of same atoms which someday were in stars. In other words, some atoms in our bodies are from stars which exploded billions of years ago.

I wonder if it is indeed true. I mean human's life begins when sperm cell fertilize egg cell. Now does that sperm cell or egg cell indeed contains some of the exact atoms from those stars?

I know little bit strange question, but would be interesting to hear if it is indeed true, that atoms in our body are same which someday were in stars.

In case you are wondering that's the video I am talking about: http://www.youtube.com/watch?v=9D05ej8u-gU

Answer 1

The chemical elements in our bodies are inherited from the Earth. The Earth was formed in a disc of gas and dust swirling around the protosun 4.5 billion years ago. The material that formed the Earth was a selection of the material from that protostellar nebula that was itself once part of a larger molecular cloud.

So the atoms in our body were once part of this molecular cloud, so we need to understand how they got there.

After the first ten minutes or so, the universe contained mainly hydrogen, helium and some traces of lithium, deuterium and tritium - and that's all. No oxygen, iron, carbon etc.

Almost all of the heavier chemical elements are made inside stars. We could stop there - the atoms of carbon, oxygen, calcium etc. in our bodies must have been made in stars, and since these atoms/nuclei are stable, they must survive unchanged (you could argue about whether their electrons get swapped about in chemical reactions etc., but since electrons are indistinguishable this hardly matters).

But how do they get into a molecular cloud and what sort of stars make these elements? A couple of answers correctly identify massive stars that explode as supernovae as important. But they are by no means the only contributor, or even the most important contributor for some elements.

If we take carbon and nitrogen, these are manufactured in nuclear reactions inside stars of even a bit less than a solar mass during the horizontal branch and asymptotic giant branch stages. These stars may be less massive and produce less C and N than massive stars, but there are many more of them. The central material is mixed to the surface during thermal pulses and the outer envelope, enriched in a variety of chemical elements, is gradually lost into space via a slow wind. This is a major source of carbon, nitrogen, fluorine, lithium and a number of heavy elements - Ba, La, Zr, Sr, Pb and many others - produced in the s-process. About 50% of the elements heavier than iron are made in the s-process, which can occur in both massive stars that explode (mainly isotopes with $A<90$) and the less massive AGB stars with slow, massive winds (elements up to lead and bismuth).

Iron, nickel and many other elements such as sulphur and silicon are also produced during type Ia supernovae. This is the detonation of a white dwarf, the end stage of a low-mass star, after mass transfer or merger. Milder novae explosions caused by the ignition of material accreted onto a white dwarf also enrich the interstellar medium.

All these different processes produce distinctive patterns of element abundances.

The enriched material is swept up by neighbouring supernova explosions, by interactions with spiral arms and other molecular clouds. It cools, condenses and collapses to form a new generation of stars.

Analysis of "presolar grains" found inside meteorites tells us what our solar system formed from. These analyses tell us that all of the above processes were important in making the chemical elements that made up the Earth and hence those in our bodies.

[Further details on the production of elements heavier than iron (including supernovae, low-mass AGB stars, colliding neutron stars etc.) can be found in my Physics SE answer to this question. ]

Answer 2

When the first atoms came into being in the early universe they were mainly hydrogen (the smallest atoms there are) and some helium. All over the universe those atoms lumped together under gravity until the pressure and temperature became so high that the hydrogen atoms fused together to form heavier elements. The reaction is nuclear fusion, and it's the engine of all stars. First hydrogen fuses to form helium, and then in a cascade helium atoms fuse to form heavier elements.

Many stars die as a supernova, without doubt the most violent explosions in the universe. The supernova which was just a single star becomes as bright as the complete galaxy it's part of. Remember that such a galaxy typically consists of 100 billion stars.

During the supernova explosion all the elements from helium to the most heavy elements are thrown into space. Later they will coalesce to form planets around new stars. So indeed, everything the earth consists of comes from such an exploding star.

And the next step is life. A single cell consists mainly of carbon, hydrogen, oxygen and nitrogen, all ultimately coming from the earth. For instance a plant will take these elements from the soil and the air, and we animals get it from plants. So the elements from the soil, which came from stars, ultimately ends up in each of our cells.

Answer 3

Almost all hydrogen nuclei (protons), some helium atomic nuclei and traces of lithium nuclei are thought to have formed early in the universe, after the big bang. Almost all other atomic nuclei are thought to have formed in stars or have decayed from atomic nuclei, which have formed in stars. A minor fraction forms by high-energy collisions with cosmic rays.

The electrons of the hull of atoms in parts formed during the big bang, part of them come into existence, when neutrons decay to protons. These neutrons may have been free neutrons, or neutrons bound in instable atomic nuclei.

Hence our body doesn't contain the exact same atoms as they formed in stars. But without stars most of the atoms besides hydrogen in our body wouldn't exist.

Our body contains many of the exact same atomic nuclei, as they formed in stars, not the exact same atoms/ions.

To be a little more precise: Our body doesn't contain many free atoms, but mainly molecules and ions.

Answer 4

Your body has hydrogen and heavier elements.

Most hydrogen in your body (really most of it) is primitive hydrogen from the origins of the Universe. Same would happen for Helium but we don't have it (almost none) on our bodies.

For all other elements, yes, they come (really most of them) from a star.

Sequence is approximately as follows:

When the Universe was young, our Galaxy was young: it was a cloud made of Hydrogen and Helium. Then, some stars (called Population III stars) were born and started burning hydrogen into helium, and on the latter stages of their lives they burned up helium into weighter elements like carbon, nitrogen, up to very small amounts of iron (the most stable element), and beyond that up to uranium.

Depending on their mass, of course. The smaller of these stars may be still around us, and the bigger ones exploded, sending these new elements to the galactic (a.k.a. interstellar) medium.

Then, from the now enriched medium, new stars were born (called Pupulation II stars). These ones had of course a lot of hydrogen and helium, but they had also some of the heavier elements. In turn, some of them are still observable (smaller ones, which last longer) and some of them exploded (bigger ones, which burn faster).

This second wave of stellar explosions enriched more the interstellar medium (gallactic medium) so a new generation of stars could be born. These are known as Pupullation I stars. Our Sun is one of them.

But not all the mass of the cloud which formed our Sun went into the Sun. Some if it made up the planets, and thus, ourselves.

So the atoms on our bodies come from the pre-planetary cloud, which consisted in original hydrogen enriched by Popullation III and Popullation II explosions.

Please note: due to chemical reactions, electrons in the atoms do not need to be the same they were while they were ejected by the stars, but the nucleus are.

Answer 5

Think about it this way, there are two options about how life began on earth: abiogenesis(life began on earth) and panspermia (life began somewhere else and from something like a meteor strike it continued to evolve on earth),at least those are the ones the are more dominant than other theories. Either way if life began to evolve on earth from matter that was on earth than it is suitable that whatever life evolved here would contain the same materials as earth, and earth originated from other starts, dust and debris that was around 4.5 billion years ago same thing for the second theory I mentioned. So I would suggest reading more on abiogenesis and panspermia it may satisfy your curiousity and answer your question.

Answer 6

Yes all of the atoms in any organism, and in fact the whole Earth, have been around for about 13.8 bn years (hydrogen, helium, lithium), since the beginning of the Universe, or have been made in various stars. Some elements were formed in supernovae, but others have been formed in other types of stellar element foundries.

Since about 4.5 bn years ago the Earth is being formed. I use 'being' since, although most already is in place, the process is still on going, meteorites and other types of material is continuing to fall down on Earth but there are also atoms leaving Earth. Most atoms that form the Earth have been here for at last 4 bn years though.

Now any organism literally builds itself from these atoms. Not only during growth, but in fact all atoms are continually being replaced in an upkeep process, which is one reason why adults still need to eat, we are continually losing atoms and thus continue to replace them with new ones.

Since some of the atoms are recent arrivals, some of our atoms might actually have been in outer space as recently as last week, but most have been part of Earth for a long time, and the atoms in our bodies have been in many more organisms. They have been in bacteria, in dinosaurs, trees, mushrooms, fish, potatoes, in trilobites, lettuce, and countless others.

Some of our atoms have been in the oceans ever since they were formed; others have been locked in rock for billions of years before they ended up in our bodies. And since they are just temporarily in us, they might be in a plant next week and in a turtle the next.

Answer 7

Because atoms are neither created nor destroyed we could be made of anything. Not only particles that use to be stars, but just particles in the air, the oxygen we breathe, the atmosphere. Because we are created from a sperm and egg cell from two people, we contain molecules from their bodies. This is a very interesting discussion.

Answer 8

I might not be that much conceptual to you, but do you believe that stars are made up of Hydrogen (and Helium too). Hydrogen is a part of all the organic compounds. We humans are made up of billions of organic compounds, which in turn do contain Carbon, Hydrogen and Oxygen as their basic element and other compounds such as Sulphur, Phosphorus and other fats. And I guess a biology student would tell you more clearly what a sperm contains and what and how do these elements ressembles to those who are in Stars.

When a star collapses, it liberates out elements such as Carbon, Iron etc. Which maybe you're talking about. So that sperm consists of the same elements that the Star had at the time of its death (well not death you might know a better word for the star's ending period).

However, this doesn't make sense that these atoms are really the exact same or the actuall ones that were in the Stars many years ago. No such theory has been provided.

What does Star contain and what it liberates: http://answers.yahoo.com/question/index?qid=20080908195830AA5Iheb

Answer 9

I will say, two years late I suppose, (lol) that on a true scientific basis, we cannot factually say yes or no to the question. You have been given excellent theories on the matter, but in order to answer that question, one would need to document and follow the life of one single atom, how it becomes whatever it becomes, and track it all the way to it's exsistance in a human body... Which we cannot do at this time. Perhaps one day? :) But not as of yet.

The question is one I've looked into thousands of times, but you must always look to the basis of what is fact. Fact is a verifiable observation and as no one has tracked and witnessed an atom from a supernova make its way to the human body, no one can merely answer 'yes' or 'no'. Not even a 'yes, mostly'.

Odds are they are the same in some form or another, but that's using the word 'odds'. You have asked an excellent question... But it cannot be answered and probably won't be in our lifetime.