IntroductionDolphins are one of the most intelligent mammals in the animal kingdom and have developed advanced, complex cognitive abilities for survival. Their brain can be measured and compared to a human and show close resemblance in cognitive features and thought processes. According to Bossley, “… many mammals and birds, nurture is added to nature, so that each generation learns necessary skills – such as migratory routes, predatory abilities, awareness of danger and more – from their elders,” which ultimately reveals how dolphins have this capability. This observation reveals that dolphins have the ability to teach their young multiple cognitive and survival skills. Some of these abilities include daily communication, self-recognition, mimicry, and also their imitation and response to certain behaviors. This reveals how complex their brains are and what they are capable of. Dolphins have developed ways in their brain to understand concepts and learning skills that proves to us how advanced their cognitive abilities are among other species. The Brain of DolphinsThe brain of dolphins and other cetaceans are larger than any other primates and are second only to human brains when measured with respect to body size, (Marino, Connor, & Fordyce, 2007). Species that have larger brains such as humans, dolphins, and chimpanzees will have these main things in common. Some commonalities shared between large brain species would be the ability to live longer, have communication in their communities, and be apart of social groups. The abilities they have developed in their brain, especially underwater species, reveal their high, complex intelligence level. According to Montgomery, the specialized cells in the brain, spindle neurons, are associated with the ability to recognize, reason, communicate, perceive, adapt to change, problem solve, and understand which are found associated and in the brains of both whales and dolphins. Dolphins often display and show active signs of these abilities in their well-developed brain. There is no appropriate way to determine the actual Intelligence quotient (IQ) of a dolphin, but there has been ways to measure it by determining the measure of relative brain size defined as the ratio between actual brain mass and predicted brain mass for an animal of a given size which is measured as “encephalization quotient (EQ),” (Dolphin Brain & Intelligence, 2017). In the human brain the EQ is 7.0 compared to other small brain animals such as the chimpanzee, elephants, and great ape which ranges from 1.8-2.3. This shows the clear difference from a small brain species compared to the dolphins EQ which is 4.2 and the closes ratio to a human brain, (Dolphin Brain & Intelligence, 2017). The higher EQ determines the intelligence level of the species, so the higher the better abilities they hold. Additionally, dolphins have the same structure as humans with their brain which can process complex abilities and also show a state of emotion. According to Lori Marino, a neurobiologist says that the dolphins limbic system is the most interesting part about this water species because it can be more complex than our own! The limbic system is so large in whales and dolphins that it erupts into the cortex in the form of an extra paralimbic lobe (Marino et. al, 2007). Unlike humans, the extra paralimbic lobe is large enough that it connects with the cortex which gives dolphins a mixture of both cognitive and emotional thinking. It is said that in this crossing of the extra paralimbic lobe and cortex could hide the hidden facts on social communication and how they develop self-awareness something most species do not develop, (2017). With the closest brain to body ratio, in respect to the human brain, dolphins have the same or even better developed cognitive abilities are some aspects quite similar to a human brain. Cross-Modal Abilities Cross-modal matching is a procedure which has been used with humans and nonhuman primates to study the relationship between their haptic (active touch) and visual senses (see reviews in Jones, 1981; Savage-Rumbaugh et al., 1988). It is found in most complex species that determines how they communicate and learn with these types of cross-modal abilities. Being able to spontaneously recognize objects across different senses increases the flexibility of a multisensory system, because the reliability of different sensory inputs depends on the environment and range (Schumacher, Burt de Perera, & Thenert, 2016). This has been found to be true in species that have a higher, more complex brain structures. Dolphins have that cross-section of the cortex and the extra limbic system that they, “In some of these cases cetaceans exhibit behaviors and abilities not found outside of the human species or found only in great apes,” (Marino, 2002). Echolocation is the ability to help dolphins see better in water which gives them the ability to develop better cognitive skills from the cross-modal abilities. According to Terjaratchi, because of water ability to travel sound at a rate of 4.5 times faster it allows dolphins to use this to their advantage while using their sonar (2008). They use their air sacs in their head to send out clicking sounds that pass through their bulbous forehead. It is then focused, and them beamed out in front of the dolphin to an object then bounce back to the dolphin. The information is received in the fat-filled cavities in the lower jaw and the nerces will transmit it back to the brain where the “picture” is then created for the dolphin to determine what they object is and the perception of it (Terjaratchi, 2008). Sensory systems are designed to pick up ecologically useful information which is in dolphins called echolocation. The echolocation in dolphins which is usually studied as a model for object recognition in sonar systems (Harley, Putman, & Roitblat, 2003). What researchers have observed is that in the dolphin’s brain it contains algorithms, which can be derived through the natural endowments or from experience, which allows dolphins to identify these objects based on sounds (Harley et. al, 2003).This helps in their survival underwaters and has been known to be evolved slowly over time for dolphins to have a sonar sensing system in their brains.Self-Recognition Ability Mirror self-recognition (MSR) is an uncommon thing in the animal kingdom. This ability was only to be found in humans and in apes. To be capable of MSR the species would have to use the mirror to investigate or be aware of their own bodies. According to Marino, dolphins are capable of MSR despite possession of unelaborated frontal lobes and a cortical organization pattern that is very different different from that of primates and humans (2002). Even though they are missing that part that is found in human brains they still can recognize himself in the mirror and have self-awareness. Dolphins have more abstract levels of self-awareness, even though the absence of the frontal lobes is missing and it is a crucial part and necessary part for self-recognition. With dolphins having this self-recognition it proves that the neuroanatomical basis is not necessary for cetaceans (Marino, 2002). But the main factors to determine whether a species have self-recognition ability and self-awareness is the encephalization level and the level of cortical connectivity which determines these complex abstract abilities. Mimicry and Imitations Dolphins have established stable communities and cultures where naturally they are mimics. They have a very social group interaction and communication that it is inevitable that with their abilities they can, “…execute synchronous motor behaviors such as “porpoising” in unison, and spontaneously imitating sounds including the whistles of others…” (Marino et. al, 2007). Dolphins abilities to execute these mimicry and imitations to certain behaviors and reactions displays cognitive abilities to understand and learn. They have both arbitrary vocal and motor imitation where they communicate vocalization in different sounds and pitch dependent on behavior. According to Reiss and McCown, there are evidence of vocal learning through spontaneous vocal mimicry by dolphins and how, “The patterns of vocal mimicry and production suggest a new model for analyzing dolphin vocalizations and vocal development with respect to signal structure and organization,” (1993). This displays that when dolphins are prompted to be trained or respond to a certain behaviors shows how they observe and will react a certain way. Or they will mimic the behavior in order to receive the same response. Social CommunicationSocial complexity and culture in dolphins and all cetaceans are arguably dependent on a complex and flexible communication system, encompassing vocal, visual, tactual, and possibly chemical signals (Marino et. al, 2007). Since dolphins are socialized species they have a complex, stable communication that they use, understand, and later teach to their young. Because they can teach their young learning and survival skills shows the high level of cognitive abilities they hold. Naturally, dolphins use their complex brain structure to have highly differentiated relationship between others in their species. They have relationships with networking between each other, hierarchy statuses, and cooperative networks (Marino et. al, 2007). Since they have socialize groups they often experience, “…impressive cultural learning of dialects, foraging sites, and foraging and feeding strategies in cetaceans,” (Marino et. al 2007). Cetaceans, which includes killer whales, dolphins, and humpback whales have a distinctive element which is multiculturalism, which means they all share the same habitat but have their own cultures within their own species. According to Marino et. al, dolphins will communicate with various pitches in vocal signals and also they will send vocal cues to others such as changes in their body posture and in tactile behaviors as well such as flipper touching and teeth ranking (2007). This form of communication can become so complex and hierarchical that it creates a highly structured system of communication. Dolphins will have complex social groups with where they communicate with one another through whistles and squeaks. They even will have different regional dialects to distinguish different groups from one another. According to Dr Susanne Shultz, an evolutionary biologist in Manchester’s School of Earth and Environmental Sciences, said: “As humans, our ability to socially interact and cultivate relationships has allowed us to colonise almost every ecosystem and environment on the planet. We know whales and dolphins also have exceptionally large and anatomically sophisticated brains and, therefore, have created a similar marine based culture (University of Manchester, 2017). This shows the parallel connection that dolphins have similar cognitive abilities, social groups, and relationship just as humans. This distinction of abilities in dolphins shows their shows their capabilities and capacity of learning and intelligence. Another form of social communication would be the different whistle types and sounds that dolphins make. According to Tejaratchi, a mother dolphin can imprint a signature whistle to her newborn in order for her to recognize him. Each dolphin will have their own signature whistles that identifies them among their peers and social groups (2008). Whistles can be use in forms of communication feeding times, alerts, and fun to one another as well as to identify one from another. According to whales.org, the greatest expression of intelligence, and whales and dolphins are among the most play of all in the animal kingdom. Dolphins have developed amazing games among one another where they could play a game of catch or jump the highest out of the water (2017). Play communication is also apart of their ability to let fun happen for them. That they have prompted and developed ways to have full-on games and Conclusion Dolphins are a highly complex species living in the waters. They have developed and gained skills that are close to and somewhat better in respect to humans. The cognitive abilities that they hold of self-recognition, self-awareness, a complex communication system between groups, and the cross-modal ability reflect the high intelligence this species has. With the closest brain to body ratio closest to humans it is intriguing to observe the abilities dolphins have and naturally how they have gain these abilities over time. Overall, dolphins have developed into a species who has learned how to adapt and use their cognitive skills. They have created a system where communication is stable and highly structured. Dolphins will often “speak” through whistles to one another and also use echolocation where they can detect objects in the water quickly. Dolphins show several signs of intelligence and cognitive abilities that are close to or somewhat similar to us humans.