What is the scientific basis for ethics? There is none. Neither is there a scientific basis for the origin of the material. The origin of the material and the origin of ethics are related.
Science is the process of observing, testing, and explaining material phenomenon. Science can explain the material but cannot explain anything prior to the material, such as the state of any existence prior to the origin of the material universe.
Attempts at such explanations are speculative and have no root in observation or experimentation and thus cannot be categorized as scientific. This is not a statement against science, rather it is recognition of the limits of useful material science. Ethics has material consequences but does not have material origins. Ethics is a function of mind. Mind has material expression but not material origin. The brain is the material conduit through which mind is expressed.
Ethics is relational. Ethics do not exist outside of relationship. Relationship has material expression, but being a function of mind, relationships, like ethics, do not have material origins.
Ethics is informational. This means that ethics exist conceptually in the mind. Information always originates in a mind. There are no exceptions. Apart from the existence of mind there can be no information, ethics, or relationship.
Ethics is spiritual. Historically, morality has its origins in the religious, from which all ethical systems spring. Without the religious, ethics have no fixed foundation. Even an atheistic ethic is religious in nature in that it is an expression of anti-religious sentiment.
Atheism has no expression of fixed ethics. An atheist may develop an ethical system, but such an ethical system is not, by nature, transcendent, thus it cannot be binding on all persons. Therefore, an atheistic ethic cannot exist as a fixed system.
Without God, ethics is situational which amounts to being no ethic at all. Imagine it this way: without God, ethics is formulated on the situational. But since situations change, ethics shift. This means ethics have no permanent, transcendent foundation, which can lead to immorality. The immoral is unethical but cannot be stated as such without a transcendent ethic. Thus, ethics without God cannot be permanently sustained.
The universe has material existence but does not have material origins. The things in the universe have material origins. But the universe itself has no material origin. If the universe appeared spontaneously out of nothing, then the universe has no material origin. If the universe was created by an intelligent agent out of nothing, then the universe still has no material origin. So whether you are a naturalist or a theist, the universe has no material origin. Therefore, the question becomes, what is the origin of the material universe? What was the nonmaterial catalyst for the beginning of its existence? In like manner we also ask, what is the nonmaterial origin of ethics if ethics has no material origins?
A nonmaterial entity of mind is the most logical answer to these questions. We call this mind, God.