Some animals such as dogs or bats can hear ultra and infrasounds while people cannot. Please explain your ans.

Answer 1

Dogs and bats have different ear structures. From focusing the sound, to the ear cannal, to the ear drum, humans just do not have the apparatus to hear such high frequency sounds.

As to why humans do not have this ability, presumably it wasn't a terribly good advantage to our ancestors. Bats can detect high frequencies for obvious reasons -- they emit them for echo location -- and high frequency sound it better at pin-pointing small insects than low frequency sounds. Wolves likely developed such hearing because they hunt mice and other rodents which make high pitch sounds.

Both wolves and bats use sound primarily as preditors. Ears are designed on top, fairly close together, and generally pointed forward. The primary purpose of their hearing it detection and tracking of prey -- mice or insects. Both wolves and bats have more effective defensive measures than hearing in defeat -- numbers, scent, excellent night vision, etc.

Human ears are on the side of the head and designed to provide warning of predators. Located on the side of the head, pointed outward, and not including large focus cones, they provide better all-round hearing and direction sense (i.e. trianglation) of sound sources. Since likely predators to human ancestors would likely be larger animals, the ability to detect high pitch sounds is not so advantageous useful in detecting an approaching lion or bear. You aren't worried about a mouse sneaking up on you.

There is also a general concensus that human ancestors went through a semi-aquatic stage. Humans have a lot of features which are common amoung aquatic mammal and not found in any other primates -- flexible spinal column, body hair in one direction, lack of fur, fat under the skin, reflex action to hold breath, nose angled to keep water from rushing in, eyes have covering to allow their use underwater, lack of good sense of smell, etc. We can also outswim most land mammals hands down. Strangely, humans can hear far better than most land mammals underwater -- many of which can't hear at all. Water in the ear cannal blocks too many sounds and prevents the inner ear from functioning in many mammals. Human ancestors likely lost their sense of hearing high frequencies because they don't carry well in water -- low frequencies being easier to hear.

Answer 2

"If God cannot be seen, heard, smelt, touched or explained...? And if he cannot be proven or disproven... What made the first Theists think there was such thing as a god in the first place?" God makes Himself known to every believer. "Think about the dreams you have while you are asleep. When you feel an emotion, or see someone and have a conversation with them, you know that they weren't really there. When you wake up, you know it was just a dream. It was you interacting with yourself subconsciously.?" God is as He is, so that one would be sure of what they believe, that is, without doubt. "So when you find strength within yourselves, or "feel" a holy presence (and its love), what makes you so sure that it's not just your mind?" Some say Christians do not have freewill, if that were so, why is it that i can think "outside the box" and you cannot. That is you are incapable of thinking in true abstract. "What makes you so absolutely certain that it's not YOU thinking there is a god who's involved with your daily life, and everyone ealse's?" Faith and more much more! The words of mere man cannot fully explain God. He has to be experienced! As a Christian, i believe, i fear not, i am and shell always be! Praise be to God. It is my prayer that God will call you unto Himself just as He has done for me.

Answer 3

Their ears are built differently externally and internally to pickup these sounds. Presumably, proto-humans who could hear them were at a disadvantage in hearing speech and warning sounds and thus died off after making no or fewer children, eliminating the trait from the gene pool.